Running SQL Commands

PostgreSQL 9.0.19 Documentation
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# 33.4. Running SQL Commands

Any SQL command can be run from within an embedded SQL application. Below are some examples of how to do that.

Creating a table:

    EXEC SQL CREATE TABLE foo (number integer, ascii char(16));
    EXEC SQL CREATE UNIQUE INDEX num1 ON foo(number);
    EXEC SQL COMMIT;

Inserting rows:

    EXEC SQL INSERT INTO foo (number, ascii) VALUES (9999, 'doodad');
    EXEC SQL COMMIT;

Deleting rows:

    EXEC SQL DELETE FROM foo WHERE number = 9999;
    EXEC SQL COMMIT;

Single-row select:

    EXEC SQL SELECT foo INTO :FooBar FROM table1 WHERE ascii = 'doodad';

Select using cursors:

    EXEC SQL DECLARE foo_bar CURSOR FOR
        SELECT number, ascii FROM foo
        ORDER BY ascii;
    EXEC SQL OPEN foo_bar;
    EXEC SQL FETCH foo_bar INTO :FooBar, DooDad;
    ...
    EXEC SQL CLOSE foo_bar;
    EXEC SQL COMMIT;

Updates:

    EXEC SQL UPDATE foo
        SET ascii = 'foobar'
        WHERE number = 9999;
    EXEC SQL COMMIT;

The tokens of the form `:`something`` are host variables, that is, they refer to variables in the C program. They are explained in Section 33.6.

In the default mode, statements are committed only when `EXEC SQL COMMIT` is issued. The embedded SQL interface also supports autocommit of transactions (similar to libpq behavior) via the `-t` command-line option to `ecpg` (see below) or via the `EXEC SQL SET AUTOCOMMIT TO ON` statement. In autocommit mode, each command is automatically committed unless it is inside an explicit transaction block. This mode can be explicitly turned off using `EXEC SQL SET AUTOCOMMIT TO OFF`.

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