Database Management: SQL Select

Please note that the following blog post provides a summary view for what you need to get done (left column) and quick examples that illustrate how to do it in SQL (right column with SQL code in red). For more information please see the resources below:

Select
SELECT *
  FROM dept
Parentheses
SELECT ename, sal, 12*(sal+100)
  FROM emp
Column Alias
SELECT ename, AS name, sal salary
  FROM emp
Eliminating Duplicate Rows
SELECT DISTINCT deptno
  FROM emp
Selecting with WHERE
SELECT ename, job, deptno
  FROM emp
  WHERE job=’Clerk’
Comparison Operators in WHERE
SELECT ename, sal, comm
  FROM emp
  WHERE sal<=comm
Between Operators in WHERE
SELECT ename, sal, comm
  FROM emp
  WHERE sal BETWEEN 1000 AND 1500
Test Values in a list
SELECT ename, empno, mgr
  FROM emp
  WHERE mgr IN (7902, 7566, 7788)
Pattern Matching in WHERE

_ is one space character *

% is trailing characters *

* is all characters

SELECT ename
  FROM emp
  WHERE ename LIKE ‘_A%’
Both conditions in WHERE are true
SELECT ename, empno, job, sal
  FROM emp
  WHERE sal>=1100
  AND job=’Clerk’
One or the other in WHERE are true
SELECT ename, empno, job, sal
  FROM emp
  WHERE sal>=1100
  OR job=’Clerk’
Not Operator in WHERE
SELECT ename, empno, job, sal
  FROM emp
  WHERE job NOT IN (’Clerk’, ’Manager’, ’Analyst,)
Sort rows
SELECT ename, job, deptno, hiredate
  FROM emp
  ORDER BY hiredate
Descending order sorting of rows
SELECT ename, job, deptno, hiredate
  FROM emp
  ORDER BY hiredate DESC
Table aliases
SELECT e.empno, e.ename, e.deptno,  d.deptno, d.loc
  FROM emp e, dept d
  WHERE e.deptno = d.deptno