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SQL Operators 101: A Comprehensive Guide to Basic Operators in SQL

24 Apr 2023
6 MIN READ
Last updated on: April 25, 2023
Table of Content SQL Operators 101: A Comprehensive Guide to Basic Operators in SQL What is a SQL operator Importance...
SQL operators
Table of Content

SQL queries are used when you work with databases to alter or modify the data and get the desired outcome. Operators in SQL are used to conduct this data processing. SQL operators in DBMS are terms that facilitate data access and retrieve the outcomes in accordance with the operators’ capabilities. 

There are numerous SQL operators available in the DBMS that makes data manipulation simpler. This article will give you a comprehensive overview of SQL operators, what they are, and more. So, read till the end. 

SQL operators

Did you just start with the basics of SQL? Are you interested in SQL and Programming? If so, check this course on Full Stack Development with Cloud for Web and Mobile to get started. 

What are SQL Operators

SQL operators are the reserved characters and words used in conjunction with the WHERE clause in the SQL query. Operators in SQL can either be unary operators or binary operators. When executing a binary operator, it needs only one operand. However, a binary operator needs two operands during execution. 

Importance of Understanding Basic SQL Operators

Connecting or linking two or more conditions together using SQL operators is crucial to establishing a condition in a SQL query. It is crucial to understand the basic SQL operators to change data and provide a result set based on the capabilities of particular SQL operators being used.

Want to learn more about SQL? Start by understanding joins in SQL

Basic SQL Operators

Typically, there are basic SQL operators used in SQL queries that you need to know about:

  • Arithmetic SQL operators
  • Logical SQL operators
  • Comparison SQL operators 

Let’s dig for more information about them in detail. 

Arithmetic Operators in SQL

The arithmetic operators in SQL enable you to carry out mathematical operations on the SQL tables’ numerical data. These SQL operators function on the numerical operands via division, multiplication, subtraction, and addition. 

Use Cases and Examples

Arithmetic SQL Operators Meaning Examples
Addition (+) Adds values across the operator side x + y will yield 50 
Multiplication (*) Multiplies values across the operator side x*y will yield 600
Modulus (%) Divides operand in the left hand by the one in the right hand and returns the remainder y%a will yield 0 
Subtraction (-) Subtracts the operand in the right hand from the one in the left hand x - y will yield -10 
Division (/) Divides the operand in the left hand by the operand in the right hand y/x will yield 1.5
Here, x is 20, and y is 30. 

SELECT 20 + 30; OUTPUT 50
 
SELECT 20 - 30; OUTPUT -10
 
SELECT 20 * 30; OUTPUT 600
 
SELECT 30 / 20; OUTPUT 1.5
 
SELECT 20 % 40; OUTPUT 0

Comparison Operators in SQL

Comparison operators in SQL are leveraged to determine whether two expressions are equivalent. You can use comparison SQL operators in a SQL query’s WHERE clause. An output of the comparison operation can be either FALSE, TRUE, or UNKNOWN. 

If either one or both parts of the expression are NULL, the comparison operator returns UNKNOWN. You can use these SQL operators on almost every type of expression except those with images, text, or text. 

Use Cases and Examples

Comparison SQL Operators Meaning Example
!=  Checks whether the two operands’ values are equal or not. If not, then the condition turns true. (x != y) is true
Checks whether the two operands’ values are equal or not. If yes, the condition turns true. (x = y) is not true 
> Checks whether the left operand value is greater than the right operand value. If so, then the condition turns true. (x > y) is not true
< Checks whether the left operand value is smaller or lesser than the right operand value. If so, then the condition turns true. (x < y) is true
<> Checks whether the two operands’ values are equivalent or not. If not, then conditions turn true. (x <> y) is true

Here is a table that we will use to perform the various comparison SQL operations for your better understanding: 

Employee ID First Name Last Name Age
1011 Aneek Burman 24
1012 Raghav  Aggarwal 26
1013 Mukesh Parsi 22
1014 Ritwik Mehra 25
1015 Rohit Sen 28

Now,

For [Equal to]: 

SELECT * FROM Employees
WHERE Age = 25


OUTPUT:

Employee ID First Name Last Name Age
1014 Ritwik Mehra 25

Logical Operators in SQL

The term’ logical operators’ refer to those SQL operators that accept two different expressions as operands and give either TRUE or FALSE as output. These SQL operators come in extremely handy when dealing with complicated SQL expressions and queries. 

Use cases and Examples

Logical SQL Operators  Meaning 
OR Two booleans are compared as expressions with Logical OR. When one of the expressions turns out to be true, this operator returns true.
AND Two booleans are compared as expressions with Logical AND. When both expressions turns out to be true, the operator returns true.
NOT Only one Boolean is taken as an argument by Logical NOT. It alters the value from true to false and vice versa.

Let’s consider the table we mentioned above to use few logical operators in SQL

SELECT * FROM Employees
WHERE Age > Any (SELECT Age FROM Employees WHERE Age > 24);

OUTPUT:

Employee ID First Name Last Name Age
1012 Raghav  Aggarwal 26
1014 Ritwik Mehra 25
1015 Rohit Sen 28

Advanced SQL Operators

Let’s look at the top advanced SQL Operators

  • String Operators
  • Null-Related Operators
  • Bitwise operators

String Operators in SQL

The string SQL operators are leveraged to perform crucial operations such as concatenation, pattern matching, etc. Pattern matching is carried out by utilizing wildcard characters such as ‘%’ and ‘_’ in conjunction with the LIKE operator to look for the precise patterns in strings. Also, by utilizing the concatenation operation, you can combine one or more columns or strings of the tables together.

To determine if a field value is NULL or not, you can run a SQL NULL check. You can run this using either IS NOT NULL or IS NULL. If a field’s value is NULL, the database did not allocate any data to that column for that row. The NULL isn’t 0 or a blank space. It stands for an unidentified or useless value.

The logical operators AND and OR cannot be used to compare them. The keyword ‘NULL’ is combined with the special operator ‘IS’ to locate values for the keyword ‘NULL’. Both character and numeric fields are capable of accepting the value NULL.

Bitwise operators in SQL

SQL operators
The Bitwise SQL operators perform the bit operations on the SQL’s integer values. You only need a basic understanding of boolean algebra to comprehend the behaviour of bitwise operators.

The two crucial logical operations that are carried out on the information kept in the SQL database tables are as follows:

  • Bitwise AND (&): The logical AND operation is carried out on the supplied Integer values by the Bitwise AND operator. With the equivalent bit from another value, this operation compares each bit of a value.
  • Bitwise OR (|): The Bitwise OR operator applies the logical OR operation on the integer values. With the equivalent bit from another value, this operation compares each bit of a value.

Challenges Faced by SQL Operators

Poor SQL

The declarative nature of SQL allows for multiple ways to express the same query and produce the same results. These variations in query construction can have a negative impact on performance.

Poor Indexes

There is a fair possibility that the underlying indexes are degrading overall performance if a table and its indexes experience much more write operations than read operations.

Locking Controversy

Locking contention may result when multiple processes attempt to update locks simultaneously on the same lock resources.

Memory Issues

Even if the server has a lot of installed memory, SQL servers typically consume a lot of it.

Need to crack an interview for a SQL-related job? Give a thorough read to these SQL interview questions for the best outcome

FAQ's

What are the major types of SQL operators?

Typically, three types of operators are used in SQL. These include: 

  • Arithmetic Operators.
  • Comparison Operators.
  • Logical Operators.

What are SQL operators, and how do they work?

When the WHERE clause is used in a SQL query, a few reserved terms in SQL are also used. In SQL, they enable us to carry out a variety of mathematical, logical, relational, bitwise, and compound operations.

To satisfy numerous conditions and improve data retrieval from the database, SQL operators fill the role of conjunctions in a SQL statement.

Can I create custom operators in SQL, and how would I do so?

Yes, you can create custom operators in SQL. To do so, you can choose either of these: 

  • Transact-SQL
  • SQL Server Management Studio
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