Oracle PLSQL Step By Step Guide
Download as PPT, PDFâą7 likesâą4,614 views
This document provides an overview of PL/SQL, Oracle's procedural language extension for SQL and the Oracle Database. It discusses key PL/SQL features like tight integration with SQL, improved performance, productivity and portability. It also covers PL/SQL programming constructs like variables, data types, control structures, procedures, functions, triggers and cursors. PL/SQL code is organized into optional declaration, executable and exception sections and allows for modular programming and error handling.
Oracle PLSQL Step By Step Guide
- 2. ïĄ Originally modeled after ADA ï§ Created for Dept. of Defense ïĄ Allows expanded functionality of database applications ïĄ Continues to improve with each new database release WWW.SRINIMF.COM 2
- 3. ïĄ Features ï§ Tight integration with SQL âȘ Supports data types, functions, pseudo-columns, etc. ï§ Increased performance âȘ A block of statements sent as a single statement ï§ Increased productivity âȘ Same techniques can be used with most Oracle products ï§ Portability âȘ Works on any Oracle platform ï§ Tighter security âȘ Users may access database objects without granted privileges WWW.SRINIMF.COM 3
- 4. ïĄ Declaration section (optional) ï§ Any needed variables declared here ïĄ Executable or begin section ï§ Program code such as statements to retrieve or manipulate data in a table ïĄ Exception section (optional) ï§ Error traps can catch situations which might ordinarily crash the program WWW.SRINIMF.COM 4
- 6. ïĄ Variables are local to the code block ïĄ Names can be up to 30 characters long and must begin with a character ïĄ Declaration is like that in a table ï§ Name then data type the semi-colon ï§ Can be initialized using := operator in the declaration ï§ Can be changed with := in the begin section ï§ Can use constraints ïĄ Variables can be composite or collection types ï§ Multiple values of different or same type WWW.SRINIMF.COM 6
- 7. ï§ CHAR ( max_length ) ï§ VARCHAR2 ( max_length ) ï§ NUMBER ( precision, scale ) ï§ BINARY_INTEGER â more efficient than number ï§ RAW ( max_length ) ï§ DATE ï§ BOOLEAN (true, false, null) ï§ Also LONG, LONG RAW and LOB types but the capacity is usually less in PL/SQL than SQL WWW.SRINIMF.COM 7
- 8. ïĄ NOT NULL ï§ Can not be empty ïĄ CONSTANT ï§ Can not be changed WWW.SRINIMF.COM 8
- 9. Age number; Last char ( 10 ); DVal Date := Sysdate; SID number not null; Adjust constant number := 1; CanLoop boolean := true WWW.SRINIMF.COM 9
- 10. ïĄ INVALID_NUMBER (ORA-01722) ï§ Attempted to store non-numeric data in a variable with a numeric data type ïĄ NO_DATA_FOUND (ORA-01403) ï§ Query resulted in no rows being found ïĄ NOT_LOGGED_ON (ORA-01012) ï§ Not currently connected to an Oracle database ïĄ TOO_MANY_ROWS (ORA-01422) ï§ A SELECT INTO statement returned more than one row WWW.SRINIMF.COM 10
- 11. ïĄ DUP_VALUE_ON_INDEX (ORA-00001) ï§ Value inserted for a primary key is not unique ïĄ VALUE_ERROR (ORA-06502) ï§ The value being placed in a variable is the wrong length or data type ïĄ ZERO_DIVIDE (ORA-01476) ï§ An attempt was made to divide a number by zero WWW.SRINIMF.COM 11
- 13. ïĄ IF-THEN ïĄ IF-THEN-ELSE ïĄ IF-THEN-ELSIF ï§ An alternative to nested IF-THEN_ELSE WWW.SRINIMF.COM 13
- 18. ïĄ The first line is called the Procedure Specification ïĄ The remainder is the Procedure Body ïĄ A procedure is compiled and loaded in the database as an object ïĄ Procedures can have parameters passed to them WWW.SRINIMF.COM 18
- 19. ïĄ Run a procedure with the PL/SQL EXECUTE command ïĄ Parameters are enclosed in parentheses WWW.SRINIMF.COM 19
- 20. ïĄ Like a procedure except they return a single value WWW.SRINIMF.COM 20
- 21. ïĄ Associated with a particular table ïĄ Automatically executed when a particular event occurs ï§ Insert ï§ Update ï§ Delete ï§ Others WWW.SRINIMF.COM 21
- 22. ïĄ Procedures are explicitly executed by a user or application ïĄ Triggers are implicitly executed (fired) when the triggering event occurs ïĄ Triggers should not be used as a lazy way to invoke a procedure as they are fired every time the event occurs WWW.SRINIMF.COM 22
- 24. ïĄ The trigger specification names the trigger and indicates when it will fire ïĄ The trigger body contains the PL/SQL code to accomplish whatever task(s) need to be performed WWW.SRINIMF.COM 24
- 26. ïĄ A triggers timing has to be specified first ï§ Before (most common) âȘ Trigger should be fired before the operation âȘ i.e. before an insert ï§ After âȘ Trigger should be fired after the operation âȘ i.e. after a delete is performed WWW.SRINIMF.COM 26
- 27. ïĄ Three types of events are available ï§ DML events ï§ DDL events ï§ Database events WWW.SRINIMF.COM 27
- 28. ïĄ Changes to data in a table ï§ Insert ï§ Update ï§ Delete WWW.SRINIMF.COM 28
- 29. ïĄ Changes to the definition of objects ï§ Tables ï§ Indexes ï§ Procedures ï§ Functions ï§ Others âȘ Include CREATE, ALTER and DROP statements on these objects WWW.SRINIMF.COM 29
- 30. ïĄ Server Errors ïĄ Users Log On or Off ïĄ Database Started or Stopped WWW.SRINIMF.COM 30
- 31. ïĄ Can specify one or more events in the specification ï§ i.e. INSERT OR UPDATE OR DELETE ïĄ Can specify one or more columns to be associated with a type of event ï§ i.e. BEFORE UPDATE OF SID OR SNAME WWW.SRINIMF.COM 31
- 32. ïĄ The next item in the trigger is the name of the table to be affected WWW.SRINIMF.COM 32
- 33. ïĄ Two levels for Triggers ï§ Row-level trigger âȘ Requires FOR EACH ROW clause âȘ If operation affects multiple rows, trigger fires once for each row affected ï§ Statement-level trigger ï§ DML triggers should be row-level ï§ DDL and Database triggers should not be row- level WWW.SRINIMF.COM 33
- 35. ïĄ Conditions Available So Multiple Operations Can Be Dealt With In Same Trigger ï§ Inserting, Updating, Deleting ïĄ Column Prefixes Allow Identification Of Value Changes ï§ New, Old WWW.SRINIMF.COM 35
- 36. ïĄ EXCEPTION Data Type Allows Custom Exceptions ïĄ RAISE Allows An Exception To Be Manually Occur ïĄ RAISE_APPLICATION_ERROR Allows Termination Using A Custom Error Message ï§ Must Be Between -20000 and -20999 ï§ Message Can Be Up to 512 Bytes WWW.SRINIMF.COM 36
- 37. ïĄ Cursors Hold Result of an SQL Statement ïĄ Two Types of Cursors in PL/SQL ï§ Implicit â Automatically Created When a Query or Manipulation is for a Single Row ï§ Explicit â Must Be Declared by the User âȘ Creates a Unit of Storage Called a Result Set WWW.SRINIMF.COM 37
- 38. Result Set MIS380 DATABASE DESIGN 4 MIS202 INFORMATION SYSTEMS 3 <Cursor MIS485 MANAGING TECHNOLOGY4 MIS480 ADVANCED DATABASE 4 WWW.SRINIMF.COM 38
- 39. ïĄ Declaring an Explicit Cursor CURSOR CursorName IS SelectStatement; ïĄ Opening an Explicit Cursor OPEN CursorName; ïĄ Accessing Rows from an Explicit Cursor FETCH CursorName INTO RowVariables; WWW.SRINIMF.COM 39
- 40. ïĄ Declaring Variables of the Proper Type with %TYPE VarName TableName.FieldName%TYPE; ïĄ Declaring Variables to Hold An Entire Row VarName CursorName%ROWTYPE; ïĄ Releasing the Storage Area Used by an Explicit Cursor CLOSE CursorName; WWW.SRINIMF.COM 40
- 41. ïĄ LOOP ⊠EXIT ⊠END LOOP ï§ EXIT with an If Avoids Infinite Loop ïĄ LOOP ⊠EXIT WHEN ⊠END LOOP ï§ Do Not Need An If to Control EXIT ïĄ WHILE ⊠LOOP ⊠END LOOP ï§ Eliminates Need for EXIT ïĄ FOR ⊠IN ⊠END LOOP ï§ Eliminates Need for Initialization of Counter WWW.SRINIMF.COM 41
- 42. ïĄ Need a Way to Fetch Repetitively ïĄ Need a Way to Determine How Many Rows to Process With a Cursor ï§ Cursor Attributes âȘ CursorName%ROWCOUNT â Number of Rows in a Result Set âȘ CursorName%FOUND â True if a Fetch Returns a Row âȘ CursorName%NOTFOUND â True if Fetch Goes Past Last Row WWW.SRINIMF.COM 42
- 43. ïĄ Processing an Entire Result Set Common ïĄ Special Form of FOR ⊠IN to Manage Cursors ïĄ No Need for Separate OPEN, FETCH and CLOSE statements ïĄ Requires %ROWTYPE Variable WWW.SRINIMF.COM 43