Schema as parameter

Question

Im trying to pass into a function the schema name as a parameter but get error re table does not exist when trying to compile
so basically i wanna do a select of the same column name and table but accross different schemas so i created function as below.
How do i do this?
FUNCTION FUN_TEST (p_schema VARCHAR2)RETURN VARCHAR2 IS
(p_result)
BEGIN
  select column
into p_result
from p_schema.table;
RETURN 'test';
END FUN_SYSLASTUSED;

Answer 1

Hi,
If you can't hard-code any identifier (such as the schema neame) into a SQLstatement, then you have to use dynamic SQL.
Here's an example:
CREATE OR REPLACE FUNCTION FUN_TEST (p_schema VARCHAR2)
RETURN VARCHAR2
IS
       p_result       VARCHAR2 (4000);         -- or whatever the length of column_1 is
       sql_txt       VARCHAR2 (100);
BEGIN
    sql_txt :=  'SELECT  column_1'
             || ' FROM    ' || p_schema || '.table_x'
         || ' WHERE   ROWNUM = 1';
    dbms_output.put_line (sql_txt || ' = sql_txt');     -- for debugging only
    EXECUTE IMMEDIATE  sql_txt
         INTO       p_result;
    RETURN  'test';
END FUN_TEST          -- name (if given) must be right
;I added the condition "WHERE ROWNUM = 1" to keep from getting errors when the table contains more than one row. What are you going to do if the table doesn't contain any rows, or if the table doesn't exist?
It's very suspicious that you know the table and column names, but not the schema. That sounds as if you are creating tables with the same structure in different schemas. Is that really a good idea? Maybe ther's a better way to design this application.