Applying Arithmetical Operations In Select Statements :

1. Arithmetic expressions can be implemented through SELECT statement.
2. Arithmetic expressions can be implemented to

• Modify the way the data is displayed.
• Perform calculations.
• Implement WHAT - IF scenarios.

3. An arithmetic expression can contain

• Simple column names
• Constant numeric values
• Arithmetic operators.

Arithmetic Operators :
1. The arithmetic operators can be used to created expressions on NUMBER and DATE data.
2. The arithmetic operators supported are

• Addition          +
• Subtraction      -
• Multiply           *
• Divide              /

3. The arithmetic operators can be used in any clause of a sql statement. Except the FROM clause.
4. SQL * Plus ignores back spaces before and after the arithmetic operator.

SQL> SELECT Empno, Ename, Sal, Sal+500 from Emp ;

 
Operator Precedence :

• Multiplication and division take priority over addition and subtractions (* ,/, +, -).
• Operators of the same prority and evaluated from left to right.
• To prioritize evaluation and to increase clarity parenthesis can be implemented.

SQL> SELECT Empno,Ename,Sal, 12*sal+100 FROM Emp;
SQL> SELECT Empno,Ename,Sal, (12*sal)+100 FROM Emp;
SQL> SELECT Empno,Ename,Sal, 12*(sal+100) FROM Emp;

Note : According to operator precedence, the evaluation of an expression can be changed.