PREPARE

Function

PREPARE creates a prepared statement.

A prepared statement is a performance optimizing object on the server. When the PREPARE statement is executed, the specified query is parsed, analyzed, and rewritten. When the EXECUTE is executed, the prepared statement is planned and executed. This avoids repetitive parsing and analysis. After the PREPARE statement is created, it exists throughout the database session. Once it is created (even if in a transaction block), it will not be deleted when a transaction is rolled back. It can only be deleted by explicitly invoking DEALLOCATE or automatically deleted when the session ends.

Precautions

None

Syntax

    
         PREPARE name [ ( data_type [, ...] ) ] AS statement;

Parameter Description

name
Specifies the name of a prepared statement. It must be unique in the current session.
data_type
Specifies the type of a parameter.
statement
Specifies a SELECT, INSERT, UPDATE, DELETE, or VALUES statement.

Examples

Create and run a prepared statement for the INSERT statement:

     
          PREPARE insert_reason(integer,character(16),character(100)) AS INSERT INTO tpcds.reason_t1 VALUES($1,$2,$3); 
EXECUTE insert_reason(52, 'AAAAAAAADDAAAAAA', 'reason 52');