MySQL Operator

An operator is a reserved word or a character used primarily in an SQL statement’s WHERE clause to perform operation(s), such as comparisons and arithmetic operations.
Operators are used to specify conditions in an SQL statement and to serve as conjunctions for multiple conditions in a statement.
1.Arithmetic operators
2.Comparison operators
3.Logical operators
4.Operators used to negate conditions

SQL Arithmetic Operators:

Operator Description Example
+ Addition – Adds values on either side of the operator a + b will give 30
Subtraction – Subtracts right hand operand from left hand operand a -b will give -10
* Multiplication – Multiplies values on either side of theoperator a * b will give 200
/ Division -Divides left hand operand by right hand operand b / a will give 2
% Modulus -Divides left hand operand by right hand operand and returns remainder b % a will give 0

SQL Comparison Operators:

Operator Description Example
= Checks if the values of two operands are equal or not, if yes then condition becomes true. (a = b) is not true.
!= Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. (a != b) is true.
<> Checks if the values of two operands are equal or not, if values are not equal then condition becomes true. (a <> b) is true.
> Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true. (a > b) is not true.
< Checks if the
value of left operand is less than the value of right operand, if yes then condition becomes true.
(a < b) is true.
>= Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true. (a >= b) is not true
<= Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true. (a<=b)is true.
!< Checks if the value of left operand is not less than the value of right operand, if yes then condition becomes false. (a!<b)is true.
!> Checks if the value of left operand is not greater than the value of right operand, if yes then condition becomes true. a !> b) is true.

The following are example illustrate the relational operators usage on tables:

Ex:

SELECT * FROM CUSTOMERS WHERE SALARY > 5000;SELECT * FROM CUSTOMERS WHERE SALARY = 2000;

SELECT * FROM CUSTOMERS WHERE SALARY != 2000;

SELECT * FROM CUSTOMERS WHERE SALARY >= 6500;

SQL Logical Operators:

Operator Description
AND The AND operator allows the existence of multiple conditions in an SQL statement’s WHERE clause
OR The OR operator is used to combine multiple conditions in an SQL statement’s WHERE clause.
NOT The NOT operator reverses the meaning of the logical operator with which it is used.Eg: NOT EXISTS, NOT BETWEEN, NOT IN, etc. This is a negatation operator

SQL AND and OR operators are used to combine multiple conditions to narrow data in an SQL statement. These two operators are called conjunctive operators.

These operators provide a means to make multiple comparisons with different operators in the same SQL statement.

Special Operators in SQL:

Operator Description
BETWEEN The BETWEEN operator is used to search for values that are within a set of values, given the minimum value and the maximum value.
EXISTS The EXISTS operator is used to search for the presence of a row in a specified table that meets certain criteria.
IN The IN operator is used to compare a value to a list of literal values that have been specified.
IS NULL The LIKE operator is used to compare a value to similar values using wildcard operators.
UNIQUE The NULL operator is used to compare a value with a NULL value. The UNIQUE operator searches every row of a specified table for uniqueness (no duplicates).