SQL WHERE Clause | What is the WHERE Clause in SQL? with Example

In this article, you will learn how to use them SQL WHERE Clause with syntax and example, Therefore when we want to restrict the SQL query results to a specified with the condition. then SQL WHERE clause comes in handy in such situations. therefore, The WHERE clause SQL to filter rows returned by a query.

Note: The WHERE clause SQL is used to filter the records.
The SQL Server WHERE clause is used to extract only those records that fulfill the specified condition.

Introduction: SQL WHERE Clause

The SQL WHERE clause is not only used in the SELECT statement, WHERE Clause also used to filter the results and apply one or multiple conditions in a SELECT, INSERT, UPDATE, or DELETE statement, etc.

The SQL WHERE clause is used to specify a condition to get the rows from the table that satisfy one or more conditions, or while fetching the data from a single table or by joining with multiple tables. furthermore, If the given condition is satisfied, then only it returns the specific value from the table. You should use the SQL WHERE clause to filter the records and fetching only the necessary records.

Therefore, When you use the SQL SELECT statement to query data against the table, then you get all the rows of that table, which is unnecessary because the application may only process a set of the rows at the time.

Syntax:

There is the basic syntax of the SELECT statement with the SQL WHERE clause is as shown below:

SELECT column1, column2, columnN
FROM table_name
WHERE condition;

Furthermore, you can specify the condition using the logical or comparison operators like >, <, =, LIKE, NOT, etc. The given below examples would make this concept clear.

Sample Demo Table: Employees

EmployeeID	Emp_Name	Father_Name	City	Salary
21	Benjamin Thakur	Elijah Connor	Nagpur	25000
22	Logan Aaron	Liam Isaiah	Mumbai	35000
23	James Hudson	Mason Ezra	Sultanpur	30000
24	William Josiah	Benjamin Hunter	Meerut	28000
25	Noah Charles	Ethan Adrian	Jhansi	32000
26	Jacob Jonathan	Henry Easton	Agra	36000
27	Jackson Elias	John Greyson	Lucknow	38000
28	Kapil Gupta	Sebastian Colton	Barabanki	40000
29	Luke Austin	Owen Dominic	Allahabad	20000
30	Jack Adam	Grayson Jordan	Delhi	40000
31	Gabriel Roman	Dylan Santiago	Noida	40000
32	Anthony Xavier	Jaxon Jose	Surajpur	45000
33	Christopher Leonardo	Andrew Bryson	Amritsar	20000
34	Joshua Jameson	Theodore Axel	Jalandhar	26000
35	Thomas sawyer	Nathan Miles	Patna	38000

Example: SQL WHERE Clause

There are the given below following SQL statement selects all the Employee from the City “Amritsar”, in the "Employees" table:

SELECT * FROM Employees
WHERE City='Amritsar';

1 2	SELECT * FROM Employees WHERE City='Amritsar';

WHERE Clause

SQL WHERE: Numeric Fields vs Text Field

Therefore, the SQL requires only single quotes around text values (most of the database systems will also allow double quotes).
However, the numeric fields should not be enclosed in quotes:

SELECT * FROM Employees
WHERE EmployeeID=25;

1 2	SELECT * FROM Employees WHERE EmployeeID=25;

Text field vs Numeric field output

Example: WHERE clause SQL combined with AND LOGICAL Operator

therefore, the SQL WHERE clause when used together with the AND logical operator, is only executed if ALL filter criteria specified are met.
Let’s see the example – Suppose we want to get a record of all the Employees the table in EmployeeID 24 and where Father_Name is Benjamin Hunter, we would use the SQL script shown below to achieve that.

SELECT * FROM Employees 
WHERE EmployeeID = 24 AND Father_Name = 'Benjamin Hunter';

1 2	SELECT * FROM Employees WHERE EmployeeID = 24 AND Father_Name = 'Benjamin Hunter';

AND LOGICAL Operator

Example: WHERE clause combined with OR LOGICAL Operator

The WHERE clause SQL, when used together with the OR operator, furthermore, it is only executed if any or the entire specified filter criteria are met.
There are the given below the following script gets all the employee in either Salary 40000 or salary 36000

SELECT * FROM Employees 
WHERE Salary = 40000 OR Salary = 36000;

1 2	SELECT * FROM Employees WHERE Salary = 40000 OR Salary = 36000;

OR LOGICAL Operator

Example: SQL WHERE clause combined with IN Keyword

The SQL WHERE clause when used together with the IN keyword only affects the rows whose values match the list of values provided in the IN keyword. therefore, IN keyword help reduces the number of OR clauses you may have to use
Therefore, there are the given below the following query gives rows where EmployeeID is either 22, 24, 28, 32 or 35

SELECT * FROM Employees 
WHERE EmployeeID IN (22,24,28,32,35);

1 2	SELECT * FROM Employees WHERE EmployeeID IN (22,24,28,32,35);

IN Keyword

Example: SQL WHERE clause combined with NOT IN Keyword

The SQL WHERE clause, when used together with the NOT IN keyword, does not affects the rows whose values match the list of values provided in the NOT IN keyword.
Therefore, there are the given below the following query gives rows where EmployeeID is either 25, 27, 29, 31, 34, or 35.

SELECT * FROM Employees 
WHERE EmployeeID NOT IN (25,27,29,31,35);

1 2	SELECT * FROM Employees WHERE EmployeeID NOT IN (25,27,29,31,35);

NOT IN Keyword

Example: WHERE clause SQL combined with COMPARISON OPERATORS

therefore, The Greater than(>), less than (<), equal to (=), not equal to (< >) all comparison operators can be used with the Where clause SQL.
= Equal To
Therefore, the given below the following script gets all the salary records from the employee table using the equal to a comparison operator.

SELECT * FROM Employees 
WHERE Salary = 40000;

1 2	SELECT * FROM Employees WHERE Salary = 40000;

Equal to operator
< Less than
Furthermore, There are the given below the following script gets all the Salaries that are Less than 40000 from the Employees table.

SELECT * FROM Employees 
WHERE Salary < 40000;

1 2	SELECT * FROM Employees WHERE Salary < 40000;

Less then operator in SQL
> Greater than
Furthermore, There are the given below the following script gets all the Salaries that are Greater than 40000 from the Employees table.

SELECT * FROM Employees 
WHERE Salary > 40000;

1 2	SELECT * FROM Employees WHERE Salary > 40000;

greater then operator in SQL
< > Not Equal To
Furthermore, There are the given below following SQL script gets all the Employees whose salary is not 40000.

SELECT * FROM Employees 
WHERE Salary < > 40000;

1 2	SELECT * FROM Employees WHERE Salary < > 40000;

NOT Equal to operator in SQL

SQL WHERE Clause Condition allowed Operators

Therefore, in the above examples, you have seen that where clause SQL allowed operators such as <, >, AND, =. Furthermore, There are given below is the complete list of operators that we can be used in the SQL where clause.

Operators List: > Greater than operator
< Less than operator
= Equal operator
>= Greater than or equal
<= Less than or equal
< > Not equal.
IN keyword- To specify a set of values
BETWEEN- To specify a range of values
LIKE- To specify a pattern

Summary: WHERE Clause

The WHERE clause SQL is used to restrict the number of rows affected by a SELECT, UPDATE, or DELETE query.
The WHERE clause can be used in conjunction with the logical operators such as AND and OR, and the comparison operators such as =, etc.
When used with the AND logical operator when all the criteria must be met.
furthermore, When used with the OR logical operator, when any of the criteria must be met.
The SQL keyword IN is used to select rows matching a list of values.
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