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SQL programmingYou can use the HCL Informix® implementation of the SQL language to develop applications for Informix® database servers.
Guide to SQL: TutorialThe Informix® Guide to SQL: Tutorial shows how to use basic and advanced structured query language (SQL) to access and manipulate the data in your databases. It discusses the data manipulation language (DML) statements as well as triggers and stored procedure language (SPL) routines, which DML statements often use.
Modify data
Data integrity
Object modes and violation detection
Definitions of object modes
Enabled mode

Enabled mode

Constraints, indexes, and triggers are enabled by default.

When a database object is enabled, the database server recognizes the existence of the database object and takes the database object into consideration while it executes an INSERT, DELETE, or UPDATE statement. Thus, an enabled constraint is enforced, an enabled index updated, and an enabled trigger is executed when the trigger event takes place.

When you enable constraints and unique indexes, if a violating row exists, the data manipulation statement fails (that is no rows change) and the database server returns an error message.

You can identify the reason for the failure when you analyze the information in the violations and diagnostic tables. You can then take corrective action or roll back the operation.

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