What are SQL Operators and how do they work?

While handling data in databases, we often tend to perform different kinds of operations to manipulate and retrieve data. SQL being the base of database management systems, offers various operators to perform such operations. In this article on SQL operators, I will discuss the various operators used in SQL, in the following sequence:

• What are operators?
• Types of Operators:

1. 1. Arithmetic Operators
   2. Comparison Operators
   3. Logical Operators

What are SQL operators?

SQL operators are reserved keywords used in the WHERE clause of a SQL statement to perform arithmetic, logical and comparison operations. Operators act as conjunctions in SQL statements to fulfill multiple conditions in a statement.

Since, there are different types of operators in SQL, let us understand the same in the next section of this article on SQL operators.

Types of SQL Operators

Arithmetic Operators

These operators are used to perform operations such as addition, multiplication, subtraction etc.

Example:

SELECT 40 + 20;

SELECT 40 - 20;

SELECT 40 * 20;

SELECT 40 / 20;

SELECT 40 % 20;

Output:

60

20

800

2

0

Well, that was about the arithmetic operators available in SQL. Next in this article on SQL operators, let us understand the comparison operators available.

Comparison Operators

These operators are used to perform operations such as equal to, greater than, less than etc.

Example:

For your better understanding, I will consider the following table to perform various operations.

Example[Use equal to]:

SELECT * FROM Students
WHERE Age = 20;

Output:

Example[Use greater than]:

SELECT * FROM students
WHERE Age > 23;

Output:

Example[Use less than or equal to]:

SELECT * FROM students
WHERE Age <= 21;

Output:

Example[Not equal to]:

SELECT * FROM students
WHERE Age > 25;

Output:

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Well, that were few examples on comparison operators. Moving on in this article on SQL operators, let us understand the various logical operators available.

Logical Operators

The logical operators are used to perform operations such as ALL, ANY, NOT, BETWEEN etc.

Example:

I am going to consider the Students table considered above, to perform a few of the operations.

Example[ANY]

SELECT * FROM Students
WHERE Age > ANY (SELECT Age FROM Students WHERE Age > 21);

Output:

Example[BETWEEN & AND]

SELECT * FROM Students
WHERE Age BETWEEN 22 AND 25;

Output:

Example[IN]

SELECT * FROM Students
WHERE Age IN('23', '20');

Output:

In this article, I have explained  only a few examples. I would say, go forward and practice a few more examples on the different types of operators to get good practice on writing SQL queries. 

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Got a question for us? Please mention it in the comments section of this article on “SQL  Operators” and I will get back to you.