Rocket UniData. Using UniData SQL. Version February 2015 UDT-810-SQLU-1

Transcription

1 Rocket UniData Using UniData SQL Version February 2015 UDT-810-SQLU-1

2 Notices Edition Publication date: February 2015 Book number: UDT-810-SQLU-7 Product version: Rocket UniData Copyright Rocket Software, Inc. or its affiliates All Rights Reserved. Trademarks Rocket is a registered trademark of Rocket Software, Inc. For a list of Rocket registered trademarks go to: All other products or services mentioned in this document may be covered by the trademarks, service marks, or product names of their respective owners. Examples This information might contain examples of data and reports. The examples include the names of individuals, companies, brands, and products. All of these names are fictitious and any similarity to the names and addresses used by an actual business enterprise is entirely coincidental. License agreement This software and the associated documentation are proprietary and confidential to Rocket Software, Inc. or its affiliates, are furnished under license, and may be used and copied only in accordance with the terms of such license. Note: This product may contain encryption technology. Many countries prohibit or restrict the use, import, or export of encryption technologies, and current use, import, and export regulations should be followed when exporting this product. 2

3 Corporate information Rocket Software, Inc. develops enterprise infrastructure products in four key areas: storage, networks, and compliance; database servers and tools; business information and analytics; and application development, integration, and modernization. Website: Rocket Global Headquarters 77 4th Avenue, Suite 100 Waltham, MA USA To contact Rocket Software by telephone for any reason, including obtaining pre-sales information and technical support, use one of the following telephone numbers. Country Toll-free telephone number United States Australia Belgium Canada China France Germany Italy Japan Netherlands New Zealand South Africa United Kingdom Contacting Technical Support The Rocket Customer Portal is the primary method of obtaining support. If you have current support and maintenance agreements with Rocket Software, you can access the Rocket Customer Portal and report a problem, download an update, or find answers in the U2 Knowledgebase. To log into the Rocket Customer Portal or to request a Rocket Customer Portal account, go to In addition to using the Rocket Customer Portal to obtain support, you can send to u2support@rocketsoftware.com or use one of the following telephone numbers. Country Toll-free telephone number North America United Kingdom/France +44(0) or +44(0) Europe/Africa +44 (0) Australia or +61 (0) New Zealand

4 Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Beta Table of Contents Table of Contents Chapter 1 Chapter 2 Chapter 3 Introduction to UniData SQL UniData SQL Commands Reference Additional Reading The UniData RDBMS Elements of the UniData Database UniData Demo Databases Overview of UniData SQL Features of UniData SQL Elements of UniData SQL UniData SQL Tables The SELECT Statement Multivalued Attributes Associations Unnesting Multivalued Attributes The UniData Dictionary Elements of Dictionary Records Getting Started Starting UniData SQL Creating a Table Inserting Data into a Table Updating Data in a Table Deleting Data from a Table Selecting Data from a Table Removing Tables Exporting Selected Data to a Sequential File Exporting Selected Data to a Temporary Table Creating and Modifying Tables Creating a New Table C:\Users\awaite\Documents\U2Doc\UniData\8.1\Source\SQLU\SQLUTOC.fm (booktoc.template) June 20, :46 pm

5 Defining Attributes Default Format and Conversion Codes Defining Attribute Name Defining Data Type Defining Virtual Attributes Defining Location Defining Display Name Defining Format Defining Value Type Defining Associations Examining Table Definitions Modifying Table Definitions ALTER TABLE Keywords Adding Attributes Modifying Tables Using the MODIFY Keyword Modifying Association Names Modifying an Association Deleting Attributes Resizing Tables Removing Tables Indexing Tables What Is Indexing? Creating and Dropping Indexes Chapter 4 Chapter 5 The Command Stack Introduction to the Command Stack Using the Command Stack Command Stack Operators Appending to an Existing Statement Changing Statements in the Stack Deleting Statements in the Stack Inserting a Statement Line into the Stack Listing Statements in the Stack Recalling a Statement in the Stack Storing Statements for Later Use Manipulating Data Inserting Data into a Table The INSERT Command Table of Contents 5

6 Inserting a Single Record Inserting Data into Specified Attributes Inserting Empty Strings and the Null Value Inserting a Record with Multiple Values Copying Multiple Records from Other Tables Updating Data in a Table The UPDATE Command Updating Specific Attributes Updating Multiple Records Updating Multivalued Attributes Adding Values and Subvalues Deleting Data from a Table The DELETE Command Deleting a Set of Records Deleting All Records in a Table Deleting Data in Multivalued Attributes Restoring the Database Chapter 6 The SELECT Statement Retrieving Data with SELECT Separation Characters Writing Simple Queries Selecting Rows from the Result Table Selecting Specific Attributes Selecting All Attributes Selecting or Excluding Duplicate Values Selecting Multivalued Attributes Selecting Multi-Subvalued Attributes Selecting Virtual Attributes Selecting Records by Specifying Record IDs Selecting Tables with FROM Qualifying Attribute Names with Table Labels Joining Tables Types of Joins How to Join Tables Inner Joins Outer Joins Unnesting Query Results with UNNEST How to Unnest Unnesting Multivalued Attributes Using UniData SQL

7 Unnesting Multi-Subvalued Attributes Unnesting Multivalued and Multi-Subvalued Attributes Selecting Records with WHERE Using Greater Than in a WHERE Clause Combining Selection Criteria with AND Combining Selection Criteria with OR Combining the AND and OR Operators Selecting Values That Do Not Meet Conditions Applying Conditions to Every Value Selecting Records That Match Patterns Searching for Patterns with the LIKE Operator Using Range Specifiers Using Wild Cards in Patterns Dictionary Conversions and the LIKE Operator LIKE Clauses and Strings Incorrect Pattern Specification The IN Operator Selecting Records within a Range Sorting Query Results Sorting in Ascending Order Sorting in Descending Order Sorting by Multiple Attributes Combining Ascending and Descending Operators Sorting Based on Multivalued Attributes Unnesting and Sorting Based on Multivalued Attributes Unnesting an Association and Sorting Sorting and Unnesting Subqueries Combining Multiple Queries into a Single Query Using ANY, ALL, and IN with Subqueries Writing Compound Queries Passing Data from Query to Subquery Group Functions Selecting Summary Information from One Group Multiple Group Functions Correct and Incorrect Group Function Use Using DISTINCT and COUNT with Attributes Writing Column Headings Selecting Summary Information from Multiple Groups Table of Contents 7

8 Including Multiple Attribute Names in a GROUP BY Clause Specifying a Search Condition for Groups Group Functions with Multivalued Attributes Expressions and Functions Arithmetic Expressions Arithmetic Functions Arithmetic Expressions and Functions in Group Functions Character String Functions Date Functions Chapter 7 Chapter 8 Creating and Querying Views What Is a View? How to Use Views How View Queries Are Processed Creating Views Creating a View from a Single Table Creating a View from Multiple Tables Creating a View Using Expressions Creating a View on a View Querying Views Optimizing Processing on View Queries Dropping Views Creating Reports Understanding UniData SQL Reports Constructing Report Columns Using the COLUMN Command Setting Up Column Headings Justifying Text in a Column Heading Controlling Column Spacing Controlling Spaces between Two Columns Controlling Spaces Between Specific Columns Formatting Report Columns Copying a Format Displaying Long Values Defining Report Titles Turning Titles On or Off Formatting Headers Formatting Footers Including Attribute Values in Headers and Footers Using UniData SQL

9 Organizing Reports by Group Creating Breaks in a Report Performing Computations at Breaks Computing Subtotals Executing Multiple Computations Computing a Grand Total Displaying and Clearing Breaks and Computations Setting the Report Environment Setting Report Parameters Wrapping Text Vertically Displaying Report Environment Parameters Preparing Complex Reports Producing a Complex Report Chapter 9 Chapter 10 Security and Administration UniData SQL Security Viewing Privileges Granting Privileges GRANT Revoking Privileges REVOKE Converting Files for UniData SQL Requirements CONVERT.SQL Converting Demo Tables UniData SQL Transaction Processing Benefits of UniData SQL TP ACID Properties UniData SQL TP and Other UniData Products UniData SQL TP and RFS UniData SQL TP and UniBasic Transaction Semantics Initiation Termination UniData SQL TP Locks Other Types of Locks Transaction Isolation Types of Transaction Errors UniData SQL Isolation Levels Table of Contents 9

10 UniData SQL TP Commands TP Commands Transaction-Initiating Commands Unsupported Commands SET DISPLAY TPMESSAGE SET TRANSACTION COMMIT ROLLBACK AUTO COMMIT LOCK TABLE Examples of UniData SQL TP Example 1 Read Committed vs. Repeatable Read Default Transaction Settings Other UniData SQL TP Considerations System Administration Performance Interaction of UniData SQL with Other Transactional Environments Tips on Transactions Optimizing Performance Limitations Chapter 11 UniData SQL and 1NF Mapping Terminology NF Mapping NF2 Data Model vs. 1NF Data Model What Is a 1NF Mapping View? Subtables Rules for Updating Subtables Primary and Foreign Keys Creating Subtables Creating Keys Examples of Read-Only Mapping Creating a View for Singlevalued Attributes Creating a View for the Multivalued Attribute Creating a View for Multivalued and Multi-Subvalued Attributes Examples of Updatable Mapping Create a Nested Level 0 Subtable Create a Nested Level 1 Subtable Using UniData SQL

11 Create a Nested Level 2 Subtable Updatable Mapping Commands CREATE SUBTABLE NLn_KEY DROP SUBTABLE Chapter 12 Appendix A Appendix B Null and Missing Values What Are Missing Values? What Are Null Values? Effects of Null and Missing Values in UniData SQL Null and Missing Values in ODBC Working with Null Values Points to Remember Examples UniData SQL Reserved Words Using Reserved Words A-2 List of Reserved Words A-3 More Table Joins Tables for Join Examples B-2 Examples of Outer Joins B-3 Full Outer Join B-3 Joining Tables on Attributes of the Same Name B-3 Full Outer Join Combined with WHERE Condition..... B-4 Joining on Multivalued Attributes B-5 Left Outer Join B-6 Left Outer Join Combined with WHERE Condition..... B-6 Right Outer Join B-7 Right Outer Join Combined with WHERE Condition..... B-7 Joining Three Tables B-8 Joining Tables in a Subquery B-8 Sorting Join Results B-9 Combining Results of Queries Containing Joins B-9 Creating a View from Joined Tables B-10 Examples of Inner Joins B-11 Stacking JOIN Clauses B-12 Combining Inner Join Results with UNION B-12 Creating a View from an Inner Join B-13 Table of Contents 11

12 Chapter 1: Introduction to UniData SQL Chapter 1 UniData SQL Commands Reference Additional Reading The UniData RDBMS Elements of the UniData Database UniData Demo Databases Overview of UniData SQL Features of UniData SQL Elements of UniData SQL UniData SQL Tables The SELECT Statement Multivalued Attributes Associations Unnesting Multivalued Attributes The UniData Dictionary Elements of Dictionary Records

13 Using UniData SQL shows you how to use the Rocket UniData implementation of Structured Query Language (SQL). UniData SQL is a query language that enables you to interact with a UniData database to organize, manage, and retrieve data stored in a database. This chapter presents an overview of the UniData SQL product. It defines database elements and introduces the unique concepts UniData uses to implement SQL with the Non-First Normal Form data model. By the time you complete this chapter, you should be able to do the following: Understand the UniData RDBMS. Identify the basic components of UniData SQL. Understand UniData dictionaries. UniData SQL Commands Reference As you go through each chapter in this manual, you will find references to the UniData SQL Commands Reference, which contains detailed information about each of the UniData SQL commands. Be sure to keep this reference guide handy. Additional Reading This manual assumes you are familiar with basic computer, operating, and SQL concepts. If you are a beginning user, you may want to refer to the following reading materials before using UniData SQL: For operating system information, see your operating system guide, or see Administering UniData. on UNIX Platforms and Administering UniData on Windows Platforms. 1-2

14 The UniData RDBMS UniData is a relational database management system (RDBMS) that enables you to easily design and build a database and create reports. It also allows ad hoc queries and provides exceptional performance. UniData s technology is based on the nested relational database model. The nested relational model extends the standard relational model from a redundant, flat-table structure to a three-dimensional database. UniData uses several access methods to store, manipulate, and report data. UniData SQL is a query language for defining and manipulating data. It contains two elements: A language for defining the structures and integrity constraints of your database, known as the data definition language (DDL). A language for declaring procedures and executable statements for operations on the database, known as the data manipulation language (DML). Elements of the UniData Database The UniData database and other relational databases consist of several components that start with basic elements and build on them to form more complex elements. See Using UniData for more detailed descriptions of these relational database components. The terms for these components are: Record Primary Key Attribute Tuple Table Database 1-3 Using UniData SQL

15 UniData Demo Databases There are two sample databases that this manual uses for example purposes. These sample databases are located in your UniData system on the Unidata installation media. This manual draws all of its examples from these sample databases. Video Classics University The Video Classics database contains records for a videotape rental store called Video Classics. This database organizes its customer and inventory information to include: Tapes in circulation. Tapes available for rent. Customer data (such as where the customers live, how old they are, and what kind of tapes they like and have checked out). Accounting information (such as daily, weekly, monthly, and yearly store income). The University database provides information most universities would use to keep track of students and staff. This database organizes the following types of student and staff information: Students majors and minors. Students courses and grades. Teachers names, titles, and courses they are teaching. 1-4

16 Overview of UniData SQL UniData SQL is an implementation of SQL. This standard, nonprocedural language enables you to create, access, and manipulate data across relational databases. Features of UniData SQL The following sections describe the main features of UniData SQL. Defining and Manipulating Data UniData SQL implements the SQL data definition language (SQL-DDL) and the data manipulation language (SQL-DML). The differences between each are: The data definition language (SQL-DDL) enables you to define or change the structure of your database, and establish and maintain the integrity constraints for your database using the commands in the following list. CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX DROP INDEX GRANT REVOKE The data manipulation language (SQL-DML) enables you to query and modify data, but not change the structure of the data that s stored in your database, using the commands in the following list. SELECT INSERT UPDATE DELETE Note: UniData SQL commands are not case-sensitive. You can enter UniData SQL commands in either uppercase or lowercase letters. 1-5 Using UniData SQL

17 The Vocabulary Table UniData supports its own account structure with a unique local repository called the vocabulary file, or VOC. This file is the backbone of the system. It is a dictionary, sometimes called the master dictionary, that contains a reference to virtually all UniData files, commands, and processes. This file forms part of the data definition environment and supporting features that are not available in other systems. See Using UniData for specific information regarding setting up and using the VOC file. Additional Highlights UniData SQL also enables you to do a variety of other functions: Supports joins between tables. Enables you to nest queries. Provides increased security of data through privileges and views. Enables extensive report formatting. Enables you to access UniData SQL from UniBasic by using the EXECUTESQL command. Enables you to work with third-party desktop tools. These highlights are discussed in detail in the chapters that follow. 1-6

18 Elements of UniData SQL UniData SQL Tables A table is a collection of interrelated attributes. Attributes become more meaningful once they are related in a table. For example, a name has little meaning by itself, but when you relate a name to other attributes like address, date of birth, and sex, you have a single relation that describes a human being. So, you need to combine a set of attributes together in a single table or relation to define a complex entity. For example, in the video store database, the data for a customer is dependent on a set of information rather than on a single piece of information; Harry Smith is a man living at 1414 W. 8th in the state of California, and he was born March 13, The CUSTOMER table in this database is actually a relation of certain attributes that define a customer. Such a relation appears in the following table. ROWS (Records, Tuples) Name Harry Smith Bonnie Partner Carrie Fischer Dick Barrie Address 1414 W. 8th 19th & Elm 640 E. Evans 2112 S. Florida City Englewood Golden Arvada Lakewood COLUMNS (Attributes, Fields) Example of a Table Tip: In UniData SQL, the term table is synonymous with the term file. 1-7 Using UniData SQL

19 The SELECT Statement To retrieve data from your database in UniData SQL, you must use SELECT statements. The SELECT statement is the foundation of the SQL language. A SELECT statement can be simple or complex; it looks very much like an English sentence. For example, the following SELECT statement tells UniData to retrieve the names of the customers in the database: sql>select NAME FROM CUSTOMER; Customer Name Jones, Bob Frobisher, Kamal Steven Spender Jamieson, Dale Chase, Carl You can embellish the SELECT statement to retrieve more data from your database by using UniData SQL clauses, like the WHERE clause. For example, in the following statement, the WHERE clause directs UniData to a table that meets specific criteria. In addition, the ORDER BY clause sorts the result of the SELECT statement by placing the customer names in alphabetic order. sql> SELECT NAME FROM CUSTOMER ORDER BY NAME ASC; Customer Name Barrie, Dick Belafonte, Harry Best, George Boorman, Rick Bowie, David Byles, Marcy... Tip: When you enter a SELECT statement, it may help you to keep track of different clauses if you put each clause on a separate line. In UniData SQL, until you place a semicolon (;) at the end of the statement, you can press ENTER without executing the statement. 1-8

20 Multivalued Attributes UniData employs a record concept that supports multivalued attributes. A multivalued attribute is an attribute that usually consists of multiple tuples or rows. Within a record, such as a customer record, you can have: An attribute for NAME that is singlevalued (since a customer has only one name). An attribute for TAPES_RENTED that is multivalued (since a customer can rent more than one tape). This use of multiple rows within an attribute is one of the things that extends the UniData capabilities beyond the First Normal Form (1NF) database. UniData allows multiple rows within a record. Associations An association is a connection between two or more attributes. A UniData table or file contains logical records that can have simple or complex attributes. A simple attribute is one that is not associated with any other attribute. A complex attribute is one that UniData uses in association with several other attributes; it identifies a connection between two or more attributes. Unnesting Multivalued Attributes You can view data stored in multivalued attributes as independent rows or tuples if they are stored in conjunction with a single record. To view data in an unnested format, use the UniData SQL UNNEST keyword. When UniData SQL displays data with an UNNEST keyword, it repeats the name of the attribute with each value. This is equivalent to other commercial SQLbased relational databases. 1-9 Using UniData SQL

21 The UniData Dictionary A dictionary is a set of records that defines the records in the data table. A dictionary provides UniData processes with the information necessary to add, display, or change data in the database. UniData SQL generates reports by referencing the dictionary when you enter a SELECT statement. Elements of Dictionary Records Dictionaries contain descriptive information about the nature of the records that make up tables. The CUSTOMER table, for example, contains almost 30 kinds of records or attributes. The dictionary for the CUSTOMER table provides details about each kind of record in dictionary records that are also called attributes. Dictionaries contain attribute records, and each dictionary attribute contains attributes that describe how UniData must view it. The following table lists the attributes that describe a dictionary attribute. Attribute Number Name Description ID The name of the attribute being described; also known as the primary key. 1 Type Type of attribute being described. Possible values are: D (Data) V (or I) (Formula) PH or ASSOC (Phrase) X (User-defined) Dictionary Attributes 1-10

22 Attribute 2 Location or Formula If D-type: Attribute 2 contains a number to identify the location of the attribute within the table. If V-type: Attribute 2 contains a formula. If PH- or ASSOC-type: Attribute 2 contains the names of the attributes that are associated. If X-type: Attribute 2 contains any user-defined information that UniData ignores. 3 Conversion A code that converts data (like dates and times) between internal format and external (display) format. 4 Display Name The column heading used by UniData SQL to display the data attribute in a report. 5 Display Format The number of spaces the display requires and the line justification. 6 Value Code Type A code for the attribute value: S Singlevalued; limits the attribute to one atomic value. MV Multivalued; allows multiple values. MS Multi-subvalued; allows multiple subvalued values. 7 Association The name of an association of multivalued and multi-subvalued attributes. Dictionary Attributes (continued) See Using UniData for detailed information on setting up and using UniData dictionaries Using UniData SQL

23 Chapter 2: Getting Started Chapter 2 Starting UniData SQL Creating a Table Inserting Data into a Table Updating Data in a Table Deleting Data from a Table Selecting Data from a Table Removing Tables Exporting Selected Data to a Sequential File Exporting Selected Data to a Temporary Table

24 This chapter introduces you to the primary statements and functions of UniData SQL and gives you hands-on practice using UniData SQL statements. Experienced UniData SQL users may want to skip this chapter. You can enter a UniData SQL statement on one or more lines as long as the last line of the statement ends with a semicolon (;). In this manual, statements may appear on several lines to make them easier to read. This chapter introduces you to UniData SQL; detailed explanations of the topics introduced here appear in the chapters that follow. The examples throughout this manual use tables in the demo databases that are provided with the UniData RBMS, and are located on your system in udthome/demo on UniData for UNIX, or udthome\demo on UniData for Windows Platforms. The UniData files have been converted with the ECL command CONVERT.SQL so that table and attribute names are ODBCcompliant. Converted files such as these are called base tables. The databases contain the following data tables. Video Classics CUSTOMER TAPES UniVersity STUDENT STAFF 2-2 Using UniData SQL Note: If you are not familiar with the login procedures of your computer system or with the basic functions of UniData, see your system administrator. For a brief overview of database management and UniData SQL, see Chapter 1, Chapter 1: Introduction to UniData SQL, or see Administering UniData on UNIX and Administering UniData on Windows Platforms. For an in-depth examination of the various tools available to build applications, as well as alternatives to structuring your database scheme, see Using UniData. By the time you complete this chapter, you should be able to do the following: Start UniData SQL. Create a table. CATEGORIES Insert, update, and delete data in a table. Select data from a table. COURSES Data Tables in Demo Tables

25 Drop a table. Export selected data to a sequential file. Export selected data to a temporary table. End a UniData SQL session. 2-3

26 Starting UniData SQL Before you use UniData SQL, go to the UniData home directory where you installed UniData. From there, change your directory to the demo account or ask your system administrator to place you in the appropriate directory. All the database tables used in the examples in this manual are in the demo directory under your UniData home account. See your system administrator for information on your home account, or see Administering UniData on UNIX or Administering UniData on Windows Platforms. When you are in the demo directory, one of the following prompts appears on your screen. Prompt Description To start UniData SQL, enter sql at the system prompt. This invokes the UniData SQL statement processor. The UniData SQL prompt appears on your screen, as follows: :sql sql> : UniData colon prompt % or $ UNIX shell prompt System Prompts From the UniData SQL prompt, you can enter any UniData SQL statement. Note: If you attempt to enter UniData SQL and receive the error message No UniData SQL privilege file in this account, creating privilege file, or if you successfully enter UniData SQL, but find you are unable to use the SELECT statement to retrieve table information from the demo database, contact your system administrator or see Chapter 9, Chapter 9: Security and Administration, for information on properly configuring your system to enable you to access the demo database. Methods for Starting UniData SQL You can enter UniData SQL in any of the following ways: Start from the UniData environment. 2-4 Using UniData SQL

27 Start from the UniData SQL prompt. Code EXECUTESQL statements in UniBasic programs. For further information, see the UniBasic Commands Reference. Submit SQL statements from the UniDesktop environment. For further information, see Developing UniData ODBC Applications, Developing UniData ObjectCall Applications, or Developing UniOLEDB Applications. Note: ObjectCall is not available beginning at UniData Execute stand-alone UniData SQL statements using the UniBasic EXECUTE command. Execute stand-alone UniData SQL statements in UniData. Execute stand-alone UniData SQL statements in paragraphs. UniData SQL Statements and the EXECUTE Command The following example shows how to code a UniData SQL statement in a UniBasic program using the EXECUTE command. As you use this statement, notice that the error messages are captured into the string variable ERR_VAR: EXECUTE "SQL SELECT * FROM STUDENT;" RETURNING ERR_VAR Note: It is important to note differences in the way the EXECUTESQL and EXECUTE commands function. The EXECUTESQL command can direct the output to a file. The READNEXTTUPLE command can later use the output so an application can go through the result set, record by record. The EXECUTE command can direct the result to the screen only, but it contains a set of options not found in EXECUTESQL, such as CAPTURING and RETURNING. For further information concerning EXECUTE and EXECUTESQL, see the UniBasic Commands Reference. UniData SQL Statements in UniData The following example shows how to execute a stand-alone UniData SQL statement in the UniData environment: SQL SELECT NAME,COURSE_NAME FROM STUDENT; 2-5

28 UniData SQL Statements in Paragraphs The following example shows a paragraph that contains UniData SQL statements. Notice that the system executes each UniData SQL statement separately, and upon completion, the UniData environment regains control, which in turn, initiates execution of the next UniData SQL statement in the paragraph. However, all the options set during the execution of the previous UniData SQL statement remain in effect when the next UniData SQL statement is executed. In this example, both TTITLE options stay in effect for the execution of the SELECT statement. ID: SAMPLE PARAGRAPH <1>:PA Example of using UniData SQL statements in a paragraph <2>:SQL TTITLE ON <3>:SQL TTITLE "Student Records" <4>:SQL SELECT * FROM STUDENT; THEN GO OK <6>:DISPLAY BAD <7>:GO FINI <8>:OK:DISPLAY OK <9>:FINI:DISPLAY END 2-6 Using UniData SQL

29 Creating a Table To create a table, use the CREATE TABLE statement. This statement has two purposes: To set up a table in your database. To define the properties of attributes in the table dictionary. The following example demonstrates how to use CREATE TABLE to create the ST_EXAM table: sql> CREATE TABLE ST_EXAM sql> (LNAME CHAR(15), sql> FNAME CHAR(15), sql> COURSE_NBR CHAR(5), sql> COURSE_GRD CHAR(1)) MODULO 1; Create file D_ST_EXAM, modulo/1,blocksize/1024 Hash type = 0 Create file ST_EXAM, modulo/1,blocksize/1024 Hash type = 0 Added "@ID", the default record for UniData to DICT ST_EXAM. 4 fields added. Create file ST_EXAM, modulo/1,blocksize/1024 For further information on creating tables, see Chapter 3, Chapter 3: Creating and Modifying Tables. You can use other UniData tools (such as UniEntry or a UniBasic program) to enter data into tables. For further information about these tools, see Using UniData, the UniData Commands Reference, the UniBasic Commands Reference, or Developing UniBasic Applications. 2-7

30 Inserting Data into a Table To add data to an existing table, use the INSERT command. The following example demonstrates how to use an INSERT statement to add a record to the COURSES table: sql> INSERT INTO COURSES sql> VALUES ("CS505","Advanced Programming",5, sql> "Gibson"); COMMIT complete. 1 record(s) created. For further information on the INSERT statement, see Chapter 5, Chapter 5: Manipulating Data. 2-8 Using UniData SQL

31 Updating Data in a Table To modify data in a database, use the UPDATE statement. For example, Mr. Codd is replacing Mr. Gibson as instructor for course CS505. You use the UPDATE statement to make the change in the COURSES table: sql> UPDATE COURSES sql> SET TEACHER = "Codd" sql> = "CS505"; COMMIT complete. 1 record(s) updated. For further information on the UPDATE statement, see Chapter 5, Chapter 5: Manipulating Data. 2-9

32 Deleting Data from a Table To eliminate a record from a table, use the DELETE statement. For example, the Computer Science Department no longer offers course CS505. Use the DELETE statement to eliminate this record from COURSES: sql>delete FROM COURSES = "CS505"; COMMIT complete. 1 record(s) deleted or updated. For further information on the DELETE statement, see Chapter 5, Chapter 5: Manipulating Data Using UniData SQL

33 Selecting Data from a Table The primary UniData SQL statement, SELECT, enables you to query your database. In its simplest form, SELECT has two parts: The SELECT clause, which specifies the attributes to access. The FROM clause, which identifies the table(s) in which the data resides. Note: Every SELECT statement must contain both the SELECT and FROM clauses. Also remember, all UniData SQL queries must end with a semicolon (;) The following SELECT statement displays data from the COURSES table: sql> FROM COURSES; COURSES Course Name Credi Teacher FA120 Finger Painting 5 Fried PY140 Abnornal Psychology 5 Masters PE100 Golf - I 3 Fisher CS105 Database Design 3 Gibson MA101 Math Principals 3 Otis FA231 Photography Practicum 3 Fried PE220 Racquetball 3 Fisher MA221 Calculus - II 5 Otis EG110 Engineering Principles 5 Carnes FA121 Watercorlors 3 Carnes EG140 Fluid Mechanics 3 Aaron CS130 Intro to Operating 5 James Systems HY101 Western Civilization 3 Otis CS100 Intro to Computer Science 3 Gibson records listed The report or list created by a SELECT statement is called the result table. Additional clauses, such as WHERE and HAVING, may further restrict the rows displayed from this result table. For further information on the SELECT statement, see Chapter 6, Chapter 6: The SELECT Statement. 2-11

34 Removing Tables When you no longer need a table, you can use the DROP TABLE statement to remove it from the database. Warning: You cannot recover a dropped table. Once UniData SQL drops a table, the data in it is lost forever. Before you use this statement, make sure you will not lose data you intend to retain. For information on temporarily storing the data before issuing a DROP TABLE statement, see Chapter 5, Chapter 5: Manipulating Data. In the following example, ST_EXAM is removed: sql> DROP TABLE ST_EXAM; Do you really want to delete file ST_EXAM?(y/n):y Deleting file D_ST_EXAM. Deleting file ST_EXAM. For further information on removing a table, see Chapter 3, Chapter 3: Creating and Modifying Tables Using UniData SQL

35 Exporting Selected Data to a Sequential File It is sometimes convenient to send the results of a query to a sequential file for these results to be used by other utilities and programs outside the UniData environment. In UniData SQL, you can use the TO keyword in a SELECT statement to do this. Using the TO keyword always requires a filename. You can also specify a path for the results file. Note: UniData SQL does not apply conversion or formatting attributes to data output to a file. The following example shows you how to send the result of the following SELECT statement to a sequential file named SAVED in the current directory: sql>select NAME,ADDRESS,CITY,STATE,ZIP,PHONE sql>from CUSTOMER sql>to SAVED; The next example shows you how to send the result of the SELECT statement shown in the previous example to a file residing in a different directory by specifying the UNIX path. sql>select NAME,ADDRESS,CITY,STATE,ZIP,PHONE sql>from CUSTOMER sql>to /usr/ud72/myaccount/results/saved; If you are using a Windows platform, you would instead specify a path such as the following: sql>to D:\UniData72\myaccount\results\saved 2-13

36 Exporting Selected Data to a Temporary Table It is sometimes convenient to save the results of a query to a temporary table that can then be used in other SELECT statements. In UniData SQL, you can use the INTO keyword in a SELECT statement to do this. As an example, you may want to use a temporary table to take a snapshot of a subset of a large UniData table and perform calculations on that subset rather than accessing the larger table. As another example, you may find it difficult or impossible to formulate a report using only one UniData SQL statement. In this case, you can first collect some intermediate data into a temporary table, then issue a SELECT statement against the temporary table to achieve desired results. Note: UniData SQL drops temporary tables when you exit UniData SQL. The following example shows you how to collect some intermediate data to a temporary table named INTERMEDIATE: sql>select NAME,ADDRESS,CITY,STATE,ZIP,PHONE sql>from CUSTOMER WHERE CITY = 'Denver' sql>into INTERMEDIATE; 2-14 Using UniData SQL

37 Chapter 3: Creating and Modifying Tables Chapter 3 Creating a New Table Defining Attributes Default Format and Conversion Codes Defining Attribute Name Defining Data Type Defining Virtual Attributes Defining Location Defining Display Name Defining Format Defining Value Type Defining Associations Examining Table Definitions Modifying Table Definitions ALTER TABLE Keywords Adding Attributes Modifying Tables Using the MODIFY Keyword Modifying Association Names Modifying an Association Deleting Attributes Resizing Tables Removing Tables Indexing Tables What Is Indexing? Creating and Dropping Indexes

38 This chapter describes how to create tables and modify table definitions in UniData SQL by using the UniData SQL statements CREATE TABLE and ALTER TABLE. By the time you complete this chapter, you should be able to do the following: Create a new table. Define attributes. Modify table definitions. Remove tables. Create indexes for tables. 3-2 Using UniData SQL

39 Creating a New Table The CREATE TABLE statement has two purposes: To set up a table in your database. To define the properties of attributes in the table dictionary. After you complete the database design, creating tables is the first step in building the database. Once you create a table and define the attributes, you can use a UniData SQL INSERT statement to enter data into the database table. Tip: You can use other UniData tools, such as UniEntry or a UniBasic program, to enter data into tables. For further information about these tools, see Using UniData, the UniData Commands Reference, the UniBasic Commands Reference, and Developing UniBasic Applications. The CREATE TABLE command performs two functions: Creates a new base table in your database. Stores the attribute definitions in the table s dictionary. UniData SQL automatically creates or primary key, as a singlevalued attribute at location 0 in the table s dictionary. For further information about the dictionary structure, see Using UniData. Note: If quotation marks are included in the definition, use single quotation marks in embedded definitions; for example: "TRANS('clients',client_nbr, 'client','x')". Syntax: CREATE TABLE table_name (attribute_definition[,attribute_definition]...) [MODULO modulo_number] [DYNAMIC [KEYONLY KEYDATA]] [TRANSACTION RECOVERABLE] 3-3

40 attribute_definition syntax: attribute_name {CHAR(size[, conv_code ]) DATE[({ date_conv time_conv })] NUMBER[({size size,n *}[, conv_code ])] LONG] [IDESC VIRTUAL ( virt_definition )] [LOC(n)] [DISP( display_name )] [FORMAT( fmt_desc )] [SM( {S MV MS} )] [ASSOC( assoc_name )] The parameters for the CREATE TABLE command are described in the following sections and in the UniData SQL Commands Reference. Examples The following statement creates a table, NEW_TAB, that has three attributes: a character field and two numeric fields. The numeric attribute MONEY_FLD contains a conversion code that formats dollars with two decimal places and prefixes negative numbers with a minus sign (-). sql> CREATE TABLE NEW_TAB sql> (NUM_FLD NUMBER, sql> CHAR_FLD CHAR(10), sql> MONEY_FLD NUMBER(10,"MD2$,-")); 3 attribute(s) added. Create file NEW_TAB, modulo/1,blocksize/1024 The following statement lists the dictionary entry for this table: sql> LISTDICT TYP LOC CONV NAME FORMAT SM ASSOC D 0 NEW_TAB 10L S NUM_FLD D 1 10R S CHAR_FLD D 2 10L S MONEY_FLD D 3 MD2$ 10R S,- 4 records listed 3-4 Using UniData SQL

41 The next statement creates a table that has the following attributes: CHAR_FLD Data type character, length of 5. DATE_FLD Data type date, formatted as mm/dd/yy. NUM_FLD Data type numeric, formatted with preceding dollar sign; including two decimal places. CHAR2_FLD Data type character, length of 12, centered within a column 25 characters wide. sql> CREATE TABLE TEST_TAB (CHAR_FLD CHAR(5), DATE_FLD DATE("D2/"), sql> NUM_FLD NUMBER(15,"MD2$"), CHAR2_FLD CHAR(12) FORMAT("25C")); 4 attribute(s) added. Create file TEST_TAB, modulo/1,blocksize/1024 The following example creates a table that contains a virtual field, VIRT_FLD, which displays the results of multiplying NUM_FLD and MONEY_FLD: sql> CREATE TABLE NEW_TAB sql> (NUM_FLD NUMBER, sql> CHAR_FLD CHAR(10), sql> MONEY_FLD NUMBER(10,"MD2$,-"), sql> VIRT_FLD NUMBER VIRTUAL("NUM_FLD * MONEY_FLD")); 4 attribute(s) added. Create file NEW_TAB, modulo/1,blocksize/1024 sql> LISTDICT TYP LOC CONV NAME FORMAT SM ASSOC D 0 NEW_TAB 10L S NUM_FLD D 1 10R S CHAR_FLD D 2 10L S MONEY_FLD D 3 MD2$ 10R S,- VIRT_FLD V NUM_FLD * MON 10R S EY_FLD 5 records listed 3-5

42 Defining Attributes You define attributes when you create a table with the CREATE TABLE command or change a table with the ALTER TABLE command. This section explains how to define an attribute when the UniData SQL syntax indicates attribute_definition. Attribute definitions consist of the following elements: Attribute name (required) Data type (required) Location Virtual attribute description Display name Format Value type specification Association description The attribute name and data type are required. You must enter the attribute name first and the data type second. The other elements are optional and you can enter them in any order. The elements are described later in this chapter. 3-6 Using UniData SQL

43 Default Format and Conversion Codes When you define an attribute with the CREATE TABLE or ALTER TABLE command, the following default conversion codes and formats are applied if you do not specify a different conversion code or format. These conversion codes and formats control the way in which attribute values are displayed. Conversion is applied first, then format. Data Type Default Conversion Default Format What is Displayed character(x) none xl x characters wide, left-justified date D2/ 10L 10 characters wide, left-justified, MM/DD/YY number none 10R 10 digits wide, right-justified long none 10R 10 digits wide, right-justified Default Attribute Display Format Syntax: attribute_name {CHAR(size[, conv_code ]) DATE[({ date_conv time_conv })] NUMBER[({size size,n *}[, conv_code ])] LONG] [IDESC VIRTUAL ( virt_definition )] [LOC(n)] [DISP( display_name )] [FORMAT( fmt_desc )] [SM( {S MV MS} )] [ASSOC( assoc_name )] Defining Attribute Name You must assign an attribute name when you define a new attribute. The following restrictions apply to attribute names: 3-7

44 Valid attribute names can contain the following types of characters: Alphabetic characters Numbers Special characters: #, and $ The first character of an attribute name must be an alphabetic character, underscore (_), or at symbol (@). If you plan to access the data in a table, subtable, or view through ODBC, do not #, or $ anywhere in the attribute name, and do not use an underscore (_) as the first character. An attribute name can be no longer than 30 characters. The name cannot be a UniData SQL reserved word. The name must be unique among attribute names within the table, subtable, or view. Defining Data Type Data type describes the type of values that the attribute contains. You can specify four data types: CHAR DATE NUMBER LONG Syntax: {CHAR(size[, conv_code ]) DATE[({ date_conv conv_code })] NUMBER[({size size,n *}[, conv_code ])] LONG] You can enter any type of data into any attribute; however, be careful when you store a different type of data in an attribute than is indicated by the data type for that attribute. If a conversion is specified, it may produce unexpected results. Also, be aware that changing the data type for an attribute in some cases results in a different display of the data than originally intended. 3-8 Using UniData SQL