Oracle Select Statement

1. SELECT STATEMENT
BASICS
Author: Renuka Parasuraman

2. Purpose
 The select statement is used to select the data from the
database.

3. Select Single Column
SELECT COLUMN_NAME
FROM TABLE_NAME;
Example:
SELECT D.DEPTNO
FROM DEPT D;

4. Select Multiple Columns
SELECT COLUMN_NAME, COLUMN_NAME
FROM TABLE_NAME;
Example:
SELECT D.DEPTNO , D.DEPT_NAME
FROM DEPT D;

5. Select Columns From Multiple Tables
SELECT *
FROM TABLE_NAME TABLE_1, TABLE_NAME TABLE_2
WHERE TABLE_1.COLUMN_NAME = TABLE_2.COLUMN_NAME;
Example:
SELECT *
FROM DEPT D, EMP E
WHERE D.DEPTNO = E.DEPTNO

6. Select All Columns
SELECT *
FROM TABLE_NAME;
Example:
SELECT *
FROM DEPT D;

7. Where Clause
SELECT COLUMN_NAME
FROM TABLE_NAME
WHERE CONDITIONS;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.DEPTNO = 10;

8. DISTINCT Rows
SELECT DISTINCT COLUMN_NAME
FROM TABLE_NAME;
Example:
SELECT DISTINCT E.DEPTNO
FROM EMP E;

9. AND Operator
SELECT COLUMN_NAME
FROM TABLE_NAME
WHERE CONDITION_1 AND CONDITION_2;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.DEPTNO = 10 AND D.LOCATION = ‘CHENNAI’;

10. OR Operator
SELECT COLUMN_NAME
FROM TABLE_NAME
WHERE CONDITION_1 OR CONDITION_2;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.DEPTNO = 10 OR D.DEPTNO = 20;

11. Select Rows With NULL values
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME IS NULL;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.LOCATION IS NULL;

12. Select Rows Without NULL values
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME IS NOT NULL;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.LOCATION IS NOT NULL;

13. ARITHMETIC OPERATORS

14. EQUAL(=) Operator
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME = VALUE;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.LOCATION = ‘CHENNAI’;

15. Greater Than(>) Operator
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME > VALUE;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.DEPTNO > 20’;

16. Lesser Than(<) Operator
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME < VALUE;
Example:
SELECT D.DEPTNO
FROM DEPT D
WHERE D.DEPTNO < 20’;

17. AGGREGATE FUNCTIONS

18. SUM
SELECT SUM(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT SUM(E.BONUS)
FROM EMP E

19. MIN
SELECT MIN(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT MIN(E.SALARY)
FROM EMP E

20. MAX
SELECT MAX(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT MAX(E.SALARY)
FROM EMP E

21. AVG
SELECT AVG(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT AVG(E.SALARY)
FROM EMP E

22. COUNT
SELECT COUNT(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT COUNT(E.BONUS)
FROM EMP E

23. COUNT(*)
SELECT COUNT(*)
FROM TABLE_NAME;
Example:
SELECT COUNT(*)
FROM EMP E

24. GROUP BY
SELECT COLUMN_NAME,
GROUP_FUNCTION(COLUMN_NAME)
FROM TABLE_NAME;
Example:
SELECT E.DEPTNO, COUNT(*)
FROM EMP E
GROUP BY E.DEPTNO;

25. HAVING CLAUSE
SELECT COLUMN_NAME,
GROUP_FUNCTION(COLUMN_NAME)
FROM TABLE_NAME
HAVING CONDITION;
Example:
SELECT E.DEPTNO, COUNT(*)
FROM EMP E
GROUP BY E.DEPTNO
HAVING COUNT(*) > 2;

26. ORDER BY ASCENDING ORDER
SELECT *
FROM TABLE_NAME
ORDER BY COLUMN_NAME, COLUMN_NAME ASC;
Example:
SELECT *
FROM EMP E
ORDER BY E.EMPTNO ASC;

27. ORDER BY DESCENDING ORDER
SELECT *
FROM TABLE_NAME
ORDER BY COLUMN_NAME, COLUMN_NAME DESC;
Example:
SELECT *
FROM EMP E
ORDER BY E.EMPTNO DESC;

28. ORDER BY COLUMN POSITION
SELECT *
FROM TABLE_NAME
ORDER BY COLUMN_ORDER, COLUMN_ORDER;
Example:
SELECT *
FROM EMP E
ORDER BY 1,2 ;

29. IN Operator
SELECT *
FROM TABLE_NAME
COLUMN_NAME IN (VALUE,VALUE);
Example:
SELECT *
FROM EMP E
WHERE E.DEPTNO IN (10,20);

30. BETWEEN Operator
SELECT *
FROM TABLE_NAME
COLUMN_NAME BETWEEN START_RANGE AND END_RANGE;
Example:
SELECT *
FROM EMP E
WHERE E.DEPTNO BETWEEN 10 AND 30;

31. ARITHMETIC FUNCTIONS

32. ABS
SELECT ABS(X) FROM DUAL;
Example:
SELECT ABS(-100), ABS(100)
FROM DUAL;

33. SIGN
SELECT SIGN(X) FROM DUAL;
Example:
SELECT SIGN(-1), SIGN(1), SIGN(0)
FROM DUAL;

34. MOD
SELECT MOD(X,Y) FROM DUAL;
Example:
SELECT MOD(100,10)
FROM DUAL;

35. FLOOR
SELECT FLOOR(X) FROM DUAL;
Example:
SELECT FLOOR(13.36)
FROM DUAL;

36. POWER
SELECT POWER(X,Y) FROM DUAL;
Example:
SELECT POWER(10,2)
FROM DUAL;

37. ROUND
SELECT ROUND(X) FROM DUAL;
Example:
SELECT ROUND(10.20)
FROM DUAL;
SELECT ROUND(10.20, 2)
FROM DUAL;

38. SQRT
SELECT SQRT(X) FROM DUAL;
Example:
SELECT SQRT(2)
FROM DUAL;