WHENEVER
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## WHENEVER

WHENEVER — specify the action to be taken when an SQL statement causes a specific class condition to be raised

## Synopsis

    WHENEVER { NOT FOUND | SQLERROR | SQLWARNING } action

## Description

Define a behavior which is called on the special cases (Rows not found, SQL warnings or errors) in the result of SQL execution.

## Parameters

See Section 36.8.1 for a description of the parameters.

## Examples

    EXEC SQL WHENEVER NOT FOUND CONTINUE;
    EXEC SQL WHENEVER NOT FOUND DO BREAK;
    EXEC SQL WHENEVER NOT FOUND DO CONTINUE;
    EXEC SQL WHENEVER SQLWARNING SQLPRINT;
    EXEC SQL WHENEVER SQLWARNING DO warn();
    EXEC SQL WHENEVER SQLERROR sqlprint;
    EXEC SQL WHENEVER SQLERROR CALL print2();
    EXEC SQL WHENEVER SQLERROR DO handle_error("select");
    EXEC SQL WHENEVER SQLERROR DO sqlnotice(NULL, NONO);
    EXEC SQL WHENEVER SQLERROR DO sqlprint();
    EXEC SQL WHENEVER SQLERROR GOTO error_label;
    EXEC SQL WHENEVER SQLERROR STOP;

A typical application is the use of `WHENEVER NOT FOUND BREAK` to handle looping through result sets:

    int
    main(void)
    {
        EXEC SQL CONNECT TO testdb AS con1;
        EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;
        EXEC SQL ALLOCATE DESCRIPTOR d;
        EXEC SQL DECLARE cur CURSOR FOR SELECT current_database(), 'hoge', 256;
        EXEC SQL OPEN cur;

        /* when end of result set reached, break out of while loop */
        EXEC SQL WHENEVER NOT FOUND DO BREAK;

        while (1)
        {
            EXEC SQL FETCH NEXT FROM cur INTO SQL DESCRIPTOR d;
            ...
        }

        EXEC SQL CLOSE cur;
        EXEC SQL COMMIT;

        EXEC SQL DEALLOCATE DESCRIPTOR d;
        EXEC SQL DISCONNECT ALL;

        return 0;
    }

## Compatibility

`WHENEVER` is specified in the SQL standard, but most of the actions are PostgreSQL extensions.

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