First understanding of PostgreSQL stored procedures, postgresql stored procedures

First understanding of PostgreSQL stored procedures, postgresql stored procedures

What is a Stored Procedure, which is defined by Baidu Encyclopedia: A Stored Procedure (Stored Procedure) is a set of SQL statements in a large database system to complete specific functions, after the first compilation, the stored procedure does not need to be re-compiled. You can specify the name of the stored procedure and provide parameters (if the stored procedure has parameters) to execute it. Stored procedures are an important object in databases. Any well-designed database application should use stored procedures.

The syntax structure of Postgresql stored procedure is as follows:
Copy codeThe Code is as follows:
Create or replace function name (parameter 1, [integer int4, integer array _ int4,…])

RETURNS return value type

$ BODY $

DECLARE

Variable Declaration

BEGIN

Function body

END;

$ BODY $

LANGUAGE 'plpgsql' VOLATILE;

The following example calls a stored procedure to automatically create a series of tables:
Copy codeThe Code is as follows:
Create or replace function create_table_for_client (id int)

RETURNS integer

$ BODY $

DECLARE

Num int4: = 0;

SQL "varchar ";

BEGIN

SQL: = 'create table _ '| id |' _ company (id int, name text )';

EXECUTE SQL;

SQL: = 'create table _ '| id |' _ employee (id int, name text) '; EXECUTE SQL;

SQL: = 'create table _ '| id |' _ sale_bill (id int, name text) '; EXECUTE SQL;

.......

Return num;

END;

$ BODY $ LANGUAGE plpgsql VOLATILE