Recipe1.4.Retrieving a Subset of Columns from a Table

Recipe 1.4. Retrieving a Subset of Columns from a Table

Problem

You have a table and want to see values for specific columns rather than for all the columns.

Solution

Specify the columns you are interested in. For example, to see only name, department number, and salary for employees:

 1 select ename,deptno,sal 2   from emp 

Discussion

By specifying the columns in the SELECT clause, you ensure that no extraneous data is returned. This can be especially important when retrieving data across a network, as it avoids the waste of time inherent in retrieving data that you do not need.