Sql procedures
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This document discusses stored procedures and functions in Oracle. It defines the key differences between procedures and functions. Procedures perform operations but do not return values, while functions return a value that can be used in computations. The document also provides the syntax for creating procedures and functions using PL/SQL and describes how to pass parameters to them.
Sql procedures
- 1. PROCEDURE : Stored Procedures and Anonymous(External) Procedures FUNCTION vs PROCEDURE : Function returns a value and the program uses the returned value for computation while Procedure doesn't return anything, it performs an operation. - Procedures are always created even if errors are there but with an error message. - SHOW ERRORS command is used to see the errors. - Source code of procedures and functions can be seen by using the command "USER_SOURCE" - select text from user_source where name='procedure_name or function_name' ---------- COMMANDS : ---------- 1. CREATE PROCEDURE : To create a procedure 2. EXECUTE : To call a procedure with its name 3. OR REPLACE : Replaces the procedure if one exists with the same name ----------------------------- CREATING A STORED PROCEDURE : ----------------------------- CREATE OR REPLACE PROCEDURE procedure_name (parameters) IS | AS BEGIN insert into table_name(parameters); commits; END; ---------------------------- CREATING A STORED FUNCTION : ---------------------------- CREATE OR REPLACE FUNCTION function_name (parameters) RETURN datatype IS | AS BEGIN executable statements; RETURN value; END; -------------- RECOMPILING : -------------- Oracle automatically compiles the invalid procedures and functions before execution. - To explicitly recompile the invalid procedures ot functions : ALTER PROCEDURE procedure_name COMPILE; - To see the status(valid/invalid) of a procedure : select status from user_objects where object_name='procedure_name'; ------------ PARAMETERS : Two types - FORMAL and ACTUAL ------------ FORMAL - parameters declared in defining the procedure ACTUAL - parameters passed while calling the procedure ---------------- PARAMTERS MODE : Three types - IN, OUT and IN OUT