NexusDB

Specify a conditional execution.

Syntax

<if statement elseif clause> ::= ELSEIF <search condition> THEN <SQL statement list>

Usage

The IF statement is used to specify a conditional execution of one or more SQL statements, and is similar in functionality to conditional IF statements found in traditional programming languages.

Notes

Examples

       DROP TRIGGER IF EXISTS enrolls_changes;        

       CREATE TRIGGER enrolls_changes

       AFTER INSERT, DELETE, UPDATE ON enrolls

       REFERENCING OLD AS o NEW AS n

       BEGIN

IF INSERTING THEN

INSERT INTO enrolls_log ( action, n1, n2, n3, n4, stamp )

VALUES ( 'Insert', n.courseID, n.sectionID, n.studentID, n.grade, CURRENT_TIMESTAMP );

ELSEIF UPDATING THEN

INSERT INTO enrolls_log ( action, o1, n1, o2, n2, o3, n3, o4, n4, stamp )

VALUES ('Update', o.courseID, n.courseID, o.sectionID, n.sectionID,

o.studentID, n.studentID, o.grade, n.grade, CURRENT_TIMESTAMP );

ELSEIF DELETING THEN

INSERT INTO enrolls_log ( action, o1, o2, o3, o4, stamp )

VALUES ( 'Delete', o.courseID, o.sectionID, o.studentID, o.grade, CURRENT_TIMESTAMP );

ELSE

SIGNAL 'An unknown trigger event was fired.';

END IF;

       END

Conformance