Professor: Dr. Shu-Ching ChenTA: Hsin-Yu Ha

Stored Procedure used in PosgreSQL

What are stored proceduresA subroutine available to applications that

access a relational database system.PL/pgSQL : A loadable procedural language.

Creates functions and trigger proceduresAdds control structuresPerforms complex computationInherits all user-defined types, functionsCan be defined to be trusted by the serverEasy to use

Why do we need stored procedure

One Query Wait, receive, process/computeDatabase

ServerIntern

et

Reduce roundtrips across the networkCan make security easier to manageAre precompiled

Structure of PL/pgSQL

Declarations (1)Declaring PL/pgSQL variable

Declarations (2)Declaring PL/pgSQL variable and assigning

values

Declarations (3)Declaring Function Parameters(1) directly give a name to the parameter in the command

(2) name ALIAS FOR $n;

Declarations (4)Directly using argument variables

Declarations (5)Attributes

%TYPE attribute

Declarations (6)Attributes

%ROWTYPE attribute

Comment syntax Single-line comments

Block comments

Basic Statements (1)Assignment

Executing a Command with NO RESULT – PERFORM

Basic Statements (2)Executing a Command with a Single-row

result

Basic Statements (3)Example

Basic Statements (4)

Basic Statements (5)FOUND – Boolean variable

Control Structures(1)RETURN expression

Control Structures(2)IF statements

IF … THENIF … THEN … ELSEIF … THEN … ELSIF … THEN … ELSE

Control Structures(3)CASE statements

CASE … WHEN … THEN … ELSE … END CASECASE WHEN … THEN … ELSE … END CASE

Control Structures(4)LOOP

EXIT

Control Structures(5)CONTINUE

WHILE

Control Structures(6)FOR (Integer Variant)

Control Structures(7)FOR (Looping through query results)

Control Structures(8)Trapping Errors

http://www.postgresql.org/docs/9.1/static/errcodes-appendix.html#ERRCODES-TABLE

Cursors (1)Declaring Cursor Variables

OPEN FOR query

Cursors (2)Using Cursors

FETCH

MOVE

NEXT PRIORFIRSTLASTABSOLUTE countRELATIVE countFORWARDBACKWORD

Cursors (3)Using Cursors

CLOSE

Returning Cursor

Cursors (4)Looping Through a Cursor’s Result

Errors and MessagesRAISE

Example

ReferencePostgreSQL Manuals PostgreSQL 9.1

http://www.postgresql.org/docs/9.1/static/index.html

Practical PostgreSQLhttp://www.faqs.org/docs/ppbook/c19610.htm

Stored Procedure in PgAdmin

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Stored Procedure in PgAdmin