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Tuesday, August 23, 2011

Arithmetic Expressions

- What is Arithmetic in SQL
  
   Arithmetic in SQL

   + Addition
   -  Subtraction
    * Multiplication
   / Division
 You can use arithmetic operators in any clause of a SQL statement except the from clause 
- Using arithmetic expressions in select statement
 For example assume if you want to calculate salary increase by 400$ you will write below select statement

SELECT EMPNO, DEPT, SAL, SAL+400
FROM EMP;


  EMPNO        SAL    SAL+400
------- ---------- ----------
   7369        800       1200
   7499       1600       2000
   7521       1250       1650
   7566       2975       3375
   7654       1250       1650
   7698       2850       3250
   7782       2450       2850
 
Rules Of Precedence
In SQL statements, arithmetic expressions are evaluated according to a standard order of operations.
Multiplication and division take priority over addition and subtraction.
If operators within an expression are of the same priority then the expression is evaluated from left to right.
Using Parentheses
You can use parentheses to change the order of evolution.    

EXAMPLE:

4*(5+5)=40

(5+5) Evaluate first
4*     Evaluate second

Arithmetic Expression with NULL Values

If you perform arithmetic on null values, the result is NULL
 EXAMPLE
10+NULL=NULL
10- NULL=NULL
NULL*10=NULL
NULL/10=NULL
10+0=10
10-0=10
0*10=10
0/10=10

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