How to use a package constant in SQL SELECT statement?

Question

How can I use a package variable in a simple SELECT query statement in Oracle?

Something like

SELECT * FROM MyTable WHERE TypeId = MyPackage.MY_TYPE
         


        

Answer 1

Note: I only tried this in Oracle 11g.

I had a similar need and found it easier to simply declare a function (without the package) to return the desired value. To put these in ddl for import, remember to separate each function declaration with the / character. For example:

CREATE OR REPLACE FUNCTION UNDEFINED_INT RETURN NUMBER AS BEGIN RETURN 2147483646; END;
/
CREATE OR REPLACE FUNCTION UNDEFINED_SHORT RETURN NUMBER AS BEGIN RETURN 32766; END;
/
CREATE OR REPLACE FUNCTION UNDEFINED_LONG RETURN NUMBER  AS BEGIN RETURN 223372036854775806; END;
/
CREATE OR REPLACE FUNCTION UNDEFINED_FLOAT RETURN FLOAT  AS BEGIN RETURN .4028233E38; END;
/
CREATE OR REPLACE FUNCTION UNDEFINED_DOUBLE RETURN BINARY_DOUBLE  AS BEGIN RETURN to_binary_double('1.7976931348623155E308'); END;
/
CREATE OR REPLACE FUNCTION UNDEFINED_STRING RETURN VARCHAR AS BEGIN RETURN '?'; END;
/

This allows you to reference the function as though it was a constant value (e.g., you don't even need the parentheses).

For example (note the to_char methods to show the precision has been preserved): SQL> select undefined_int from dual;

UNDEFINED_INT
-------------
   2147483646

SQL> select undefined_string from dual;

UNDEFINED_STRING
--------------------------------------------------------------------------------
?

SQL> select undefined_double from dual;

UNDEFINED_DOUBLE
----------------
      1.798E+308

SQL> select to_char(undefined_double,'9.999999999999999EEEE') from dual;

TO_CHAR(UNDEFINED_DOUBL
-----------------------
 1.797693134862316E+308

SQL> select to_char(undefined_double,'9.99999999999999999EEEE') from dual;

TO_CHAR(UNDEFINED_DOUBLE,
-------------------------
 1.79769313486231550E+308