28 DBMS_DB_VERSION

Using DBMS_DB_VERSION

• Overview

• Constants

Overview

The DBMS_DB_VERSION package specifies the Oracle version numbers and other information useful for simple conditional compilation selections based on Oracle versions.

The package for the Oracle Database 10g Release 2 version is shown below.

PACKAGE DBMS_DB_VERSION IS
   VERSION CONSTANT PLS_INTEGER := 10; -- RDBMS version number
   RELEASE CONSTANT PLS_INTEGER := 2;  -- RDBMS release number
   ver_le_9_1    CONSTANT BOOLEAN := FALSE;
   ver_le_9_2    CONSTANT BOOLEAN := FALSE;
   ver_le_9      CONSTANT BOOLEAN := FALSE;
   ver_le_10_1   CONSTANT BOOLEAN := FALSE;
   ver_le_10_2   CONSTANT BOOLEAN := TRUE;
   ver_le_10     CONSTANT BOOLEAN := TRUE;
END DBMS_DB_VERSION;
 

The boolean constants follow a naming convention. Each constant gives a name for a boolean expression. For example:

• VER_LE_9_1 represents version <= 9 and release <= 1

• VER_LE_10_2 represents version <= 10 and release <= 2

• VER_LE_10 represents version <= 10

A typical usage of these boolean constants is:

$IF DBMS_DB_VERSION.VER_LE_10 $THEN
   version 10 and earlier code
$ELSIF DBMS_DB_VERSION.VER_LE_11 $THEN
   version 11 code
$ELSE
   version 12 and later code
$END

This code structure will protect any reference to the code for hypothetical version 12. It also prevents the controlling package constant DBMS_DB_VERSION.VER_LE_11 from being referenced when the program is compiled under version 10. A similar observation applies to version 11. This scheme works even though the static constant VER_LE_11 is not defined in version 10 database because conditional compilation protects the $ELSIF from evaluation if DBMS_DB_VERSION.VER_LE_10 is TRUE.

Constants

The DBMS_DB_VERSION package contains different constants for different Oracle Database releases. The Oracle Database 10g Release 2 version of the DBMS_DB_VERSION package uses the constants shown in Table 28-1.

Examples

This example uses conditional compilation to guard new features.

CREATE OR REPLACE PROCEDURE whetstone IS
 
 -- Notice that conditional compilation constructs
 -- can interrupt a regular PL/SQL statement.
 -- You can locate a conditional compilation directive anywhere
 -- there is whitespace in the regular statement.

 SUBTYPE my_real IS
    $IF DBMS_DB_VERSION.VER_LE_9 $THEN NUMBER
                                 $ELSE BINARY_DOUBLE
    $END;

 t  CONSTANT my_real := $IF DBMS_DB_VERSION.VER_LE_9 $THEN 0.499975 
                                                     $ELSE 0.499975d 
                        $END;

 t2 CONSTANT my_real := $if DBMS_DB_VERSION.VER_LE_9 $THEN 2.0
                                                     $ELSE 2.0d
                        $END;

 x  CONSTANT my_real := $IF DBMS_DB_VERSION.VER_LE_9 $THEN 1.0
                                                     $ELSE 1.0d
                        $END;

 y  CONSTANT my_real := $IF DBMS_DB_VERSION.VER_LE_9 $THEN 1.0
                                                     $ELSE 1.0d
                        $END;
 
 z  MY_REAL;
 
 PROCEDURE P(x IN my_real, y IN my_real, z OUT NOCOPY my_real) IS
   x1 my_real;
   y1 my_real;
 BEGIN
   x1 := x;
   y1 := y;
   x1 := t * (x1 + y1);
   y1 := t * (x1 + y1);
   z := (x1 + y1)/t2;
 END P;
BEGIN
 P(x, y, z);
 DBMS_OUTPUT.PUT_LINE ('z = '|| z);
END whetstone;
/