Dynamic SQL with pgsql, how to?

Hi,

I need to write some dynamic SQL in pgsql.

I have to do something like this:

[code=SQL Server]
    SET @STRINGN = @STRINGN + ' AND A.' + @CAMPOFECINI + ' IN (SELECT MAX(B.' + @CAMPOFECINI + ')
            FROM ' + @TABLA + ' B
            WHERE B.ID_SOCIEDAD = A.ID_SOCIEDAD
            AND B.ID_EMPREGAD = A.ID_EMPREGAD'
    IF @F_ALTA IS NOT NULL
        SET @STRINGN = @STRINGN + ' AND B.DAT_INI_ACT_EMP = A.DAT_INI_ACT_EMP'
    SET @STRINGN = @STRINGN + ')'
       EXEC sp_executesql @STRINGN,
                N'@FINI2 datetime out, @FFIN2 datetime out, @CAMP2 varchar(50) out',
                @FINI out, @FFIN out , @CAMP out
[/code]

There is documentation on how can I do this in pgsql?

Best Regards,