Question

How can I put a table name dynamically in a query?

Suppose I have a query as shown below:

Select a.amount
      ,b.sal
      ,a.name
      ,b.address 
from  alloc a 
     ,part b 
where a.id=b.id;

In the above query I want to use a table dynamically (part b if the database is internal, p_part b if the database if external).

I have a function that returns which database it is. Suppose the function is getdatabase();

select decode(getdatabase(),'internal','part b','external','p_part b')
from  dual;

How can I use this function in my main query to insert the table name dynamically into the query?

I don’t want to implement this using the primitive way of by appending strings to make a final query and then open cursor with that string.

Answer 1

I don’t want to implement this with primitive way of by appending
strings to make a final query and then open cursor with that string .

That’s really the only way you can do it. It’s not possible to use a variable or function call for the table name when using a regular PL/SQL SQL block, you have to use dynamic SQL.

Refer to Oracle documentation for more details:
http://docs.oracle.com/cd/B10500_01/appdev.920/a96590/adg09dyn.htm

Here’s an example from the doc:

EXECUTE IMMEDIATE 'SELECT d.id, e.name
        FROM dept_new d, TABLE(d.emps) e  -- not allowed in static SQL
                                          -- in PL/SQL
        WHERE e.id = 1'
        INTO deptid, ename;