Transact SQL & Stored Procedure

Transcription

1 Transact SQL & Stored Procedure How to code in Microsoft SQL Server Training Division New Delhi

2 What is Transact-SQL? Programming language for SQL Server Standard database manipulation language SELECT, INSERT, UPDATE CREATE TABLE, CREATE PROCEDURE Use of variable in SQL statement =firstname from customer_data Program flow Control such as IF-ELSE, CASE, WHILE LOOPS Can write dynamic SQL to perform the same function as a procedural programming language do. ANSI 92 Compliant with Extensions

3 Why would I use it? Reporting Let server do the Computation Only return final data for report/program Business Logic Batch processing Server side processing

4 Where do I write the code? ISQL/OSQL (script as a text file) Query Analyzer Stored Procedure (Database) Triggers ( tables)

5 Transact-SQL Language Data retrieval and modification (DML) Data definition language (DDF) Variables Control of flow

6 Data Definition Language Language to create Database Create Database Mydb Alter Database mydb Drop Database mydb Language to create tables, indexes, etc. CREATE TABLE customer_data (cutomer_id samllint, first_name char(20), last_name char(20), phone char(10)) ALTER table Drop Table

7 Data Retrieval and Modification Retrieval SELECT JOINS and FROM WHERE GROUP BY, HAVING, and Aggregate Functions ORDER BY PRINT char(10) =first_name from customer_data where customer_id=1234 PRINT Hello World PRINT My SQL Server Version is

8 Data Retrieval and Modification Modification INSERT UPDATE DELETE

9 Variables Support Two type of Variable. Local Variable Scope is limited to current batch Special names All variable names must begin All variables must be Declared INTEGER AS CHAR(20) Setting variables is just like retrieving data = 99 RAJENDRA = RAJENDRA

10 Variables Global Variables SQL Server creates and maintains Not user definable Have

11 Datatypes Binary (binary, varbinary) Character (char, varchar) Datetime Floating Point (decimal, numeric, float, real) Integer (int, smallint, tinyint) Monetary (money, smallmoney) Bit Timestamp User-defined datatypes Text Image

12 Control of Flow IF...ELSE Can be basic or complex IF. Unlimited embedding of IFs WHILE Basic structure to loop until condition is met. GOTO BEGIN END RETURN Allows integer values to be passed out of procedure back to calling procedure

13 Expressions and built in functions Operators System functions ISNULL Wild cards and the LIKE operator

14 Stored Procedures A stored procedure consists of one or more SQL statements that perform a unit of work When Executed it compiled into an execution plan which contains two parts; one part that contains the code to be executed, and one part that contains the variables and parameters that are to be used by the code. Can accept variables Return values Multiple users and programs can execute the same stored procedures Can call other procedures EXEC spdosomething

15 Stored Procedure Maintenance becomes easier because we can change one stored procedure and it immediately becomes effective for all users and programs. Once a stored procedure is executed, it is placed in SQL Server cache. This means that subsequent executions are executed from cache. Greater Security. Low Network Traffic

16 Stored Procedure Create Stored Procedure Create procedure procedure_name datatype, length, output) As SQL Statement Execute a Stored Procedure Execute procedure_name (@parameter_name=value output) With recompile

17 Calling a Stored Procedure Set Parameter=command.createParameter (Name, type, Direction, size, value) Name=The Name of the Parameter Type=The Data Type of the Parameter Direction= adparaminput adparamoutput adparaminputoutput adparamreturnvalue Size=The Size of the Parameter Value=The value of the Parameter

18 System stored procedures sp_who sp_help sp_lock sp_password sp_rename

19 Cursors Cursors allow a developer to process records one at a time. Similar to ADO or RDO processing in VB or Access Very flexible - but there s a catch. Usually less efficient than regular SQL queries. DECLARE cursor_name CURSOR [LOCAL GLOBAL] [FORWARD_ONLY SCROLL] [STATIC KEYSET DYNAMIC FAST_FORWARD] [READ_ONLY SCROLL_LOCKS OPTIMISTIC] [TYPE_WARNING] FOR select_statement [FOR UPDATE [OF column_name [,...n]]]