SQL. by Steven Holzner, Ph.D. ALPHA. A member of Penguin Group (USA) Inc.

Transcription

1 SQL by Steven Holzner, Ph.D. A ALPHA A member of Penguin Group (USA) Inc.

2 Contents Part 1: Mastering the SQL Basics 1 1 Getting into SQL 3 Understanding Databases 4 Creating Tables Creating Rows and Columns in Tables 6 Adding Primary Keys 9 Getting Your Database Ready 10 If You Don't Already Have a DBMS 10 If You Already Have a DBMS 11 Introducing SQL 11 Creating a Database 12 Creating a Table 13 Adding Data to a New Table 16 Accessing Data from a Table 17 Adding a WHERE clause 18 Adding an IN clause 19 ^ 2 Storing Data in Tables 23 All About Tables 24 Creating a Table 25 Working with Data Types 27 Working with Constraints 31 Creating Our Example Table 33 Adding Data to a Table 35 Modifying a Column's Data Type 37 Renaming a Column 38 Adding Columns to a Table 38 Deleting Columns 39 Renaming a Table 40 Deleting a Table 40 3 Retrieving Your Data 43 Retrieving Columns from a Table 44 Retrieving Single Columns 46 Retrieving Multiple Columns. 47

3 The Complete Idiot's Guide to SQL Using Expressions 49 Using Function Calls 49 Using System Values 51 Using Special Constructs 52 Using Operators 53 2: Crunching Your Data 55 4 Sorting Your Data 57 Sorting 57 Sorting on Single Columns 58 Sorting on Multiple Columns 60 Sorting by Column Position 61 Specifying Sort Order 63 Advanced Sorts 64 5 Filtering Your Data 67 Using Comparison Operators 68 Using BETWEEN 70 Checkingfor NULL 71 Using IN and NOT IN 72 Using LIKE and NOT LIKE 73 Using SIMILAR TO 75 6 Getting More Filtering Power 77 Checking Every Result with ALL 78 Checking Any Result with ANY 78 Using SOME in Place of ANY 79 Checking Whether Anything Was Returned with EXISTS 81 Checking for One-of-a-Kindness with UNIQUE 82 Using UNIQUE in the WHERE clause 82 Using UNIQUE in the SELECT Statement 83 Checking for One-of-a-Kindness with DISTINCT 83 Using DISTINCT in the WHERE Clause 83 Using DISTINCT in the SELECT Statement 84 Checking Time Intervals with OVERLAPS 85 Checking for Specific Records with MATCH 85 Insisting All Clauses Be True with AND 86 Choosing Any Clause with OR 87 Negating Conditions with NOT 89

4 Contents vii 7 Updating Your Data 91 Updating Your Data 91 Updating a Single Table Cell with New Data 92 Updating Multiple Cells 93 Updating All Rows with the Same Data 95 Inserting Data from a Query 95 Inserting Rows from a Query 96 Inserting Partial Data into a Row 97 Copying Whole Tables 98 Copying Partial Tables 100 Deleting Rows 101 Deleting All Rows 103 Deleting a Table 103 Adding a New Column 104 Deleting a Column 104 Adding a Column with System Date 105 Modifying Columns 106 Renaming a Table 106 Adding an Index SQL's Built-in Functions 109 Getting to Know the Built-in Functions 110 Using the System Functions 110 Using the Numeric Functions Ill BIT-LENGTHO, CHAR_LENGTH(), and OCTET_LENGTH() 112 EXTRACTQ 113 POSITIONQ 114 Using the String Functions 115 CONCATENATEQ 115 CONVERTQ and TRANSLATEQ 116 LOWER() and UPPERQ 117 SUBSTRINGQ U8 TRIMQ 119 DBMS-Specific Functions 120 Oracle 121 SQLServer 124 MySQL 126 PostgreSQL 130

5 viii The Complete Idiot's Guide to SQL Part 3: In-Depth Data Handling Joining Tables 135 Using Joins 135 Creating a Join 136 Why Joins? 140 Inner Joins 141 Joining Multiple Tables. 141 Using Aliases 142 Using Different Joins 144 SelfJoins 144 Natural Joins 145 Outer Joins Aggregating and Grouping Data 149 Using the Aggregating Functions 149 AVGQ Returns the Average Value 150 COUNTQ Returns the Number ofrows 150 MAX() and MINQ Return the Largest and Smallest Value 152 SUMQ Returns the Sum 153 Aggregating on Distinct Values 154 Creating Groups 155 Using Aggregate Functions on Groups 156 Nesting Groups 157 Filtering Groups 157 Grouping and Sorting Views, Unions, and Variables 161 Understanding Views 162 Creating Views 163 Using Views to Simplify Joins 164 Reformatting Retrieved Data 166 Filtering Out Unwanted Data 168 Using Views and Calculated Fields 170 Using Unions 171 Deleting Views 174 Understanding Variables 174

6 END UNTIL Contents ix Part 4: Power Techniques T79 12 Stored Procedures and Cursors 181 Understanding Procedures 181 Creating a Procedure 182 Executing SQLfrom Procedures 183 Returning Data from Passing Procedures 185 Data to Procedures 188 Using Local Variables 190 Calling Procedures from Procedures 191 Dropping Procedures 192 Understanding Cursors 192 Fetching Data with Cursors 193 Moving to the Next Record with Cursors Using Transactions 197 Understanding Transactions 198 Performing Transactions 198 Using Rollbacks 200 Using Commit 201 Using Savepoints Understanding Constraints and Triggers 207 Using Constraints 207 Using Primary Keys 208 Using Foreign Keys 210 Using Unique Constraints 214 Using Check Constraints 215 Using NOT NULL 217 Creating Triggers 218 Dropping Triggers Advanced SQL Topics 223 Using IF... THEN 224 Using ELSE 226 Using CASE... CASE 228 Using LOOP and LEAVE 231 Using WHILE 233 Using REPEAT Using ITERATE 237

7 16 Creating and Administrating User Accounts in SQL 241 Creating New User Accounts 241 Creating User Accounts -with No Password 242 Creating User Accounts with Passwords 244 Granting Privileges 246 Granting All Privileges 249 Specifying Which Database the User Has Privileges On Specifying Which Table the User Has Privileges On 254 Granting Specific Privileges 257 Letting Users Grant Privileges 259 Appendixes A Glossary 261 B Using Different DBMSes with the Example SQL 263 Index 267