The document provides an overview of the SELECT statement in SQL and its usage for selecting data from database tables. It describes how to select single columns, multiple columns, columns from multiple tables, and all columns. It also covers the WHERE clause, DISTINCT, AND/OR operators, NULL values, arithmetic operators, aggregate functions, GROUP BY, HAVING, and ORDER BY. Examples are given for each concept.

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;