MySQL WHERE Clause: AND, OR, IN, NOT IN Query Example

By : Marcus Allen Marcus Allen
Hours Updated

What is WHERE Clause in MySQL?

WHERE Clause in MySQL is a keyword used to specify the exact criteria of data or rows that will be affected by the specified SQL statement. The WHERE clause can be used with SQL statements like INSERT, UPDATE, SELECT, and DELETE to filter records and perform various operations on the data.

We looked at how to query data from a database using the SELECT statement in the previous tutorial. The SELECT statement returned all the results from the queried database table.

They are however, times when we want to restrict the query results to a specified condition. The WHERE clause in SQL comes handy in such situations.

WHERE clause in MySQL
WHERE clause in MySQL

WHERE clause Syntax

The basic syntax for the WHERE clause when used in a MySQL SELECT WHERE statement is as follows.

SELECT * FROM tableName WHERE condition;

HERE

  • “SELECT * FROM tableName” is the standard SELECT statement
  • “WHERE” is the keyword that restricts our select query result set and “condition” is the filter to be applied on the results. The filter could be a range, single value or sub query.

Let’s now look at a practical example.

Suppose we want to get a member’s personal details from members table given the membership number 1, we would use the following script to achieve that.

SELECT * FROM `members` WHERE `membership_number` = 1;

Executing the above script in MySQL workbench on the “myflixdb” would produce the following results.





membership_number
full_names
gender
date_of_birth
physical_address
postal_address
contct_number
email






1
Janet Jones
Female
21-07-1980
First Street Plot No 4
Private Bag
0759 253 542
janetjones@yagoo.cm

WHERE clause combined with – AND LOGICAL Operator

The WHERE condition in MySQL when used together with the AND logical operator, is only executed if ALL filter criteria specified are met.

Let’s now look at a practical example – Suppose we want to get a list of all the movies in category 2 that were released in 2008, we would use the script shown below is achieve that.
SELECT * FROM `movies` WHERE `category_id` = 2 AND `year_released` = 2008;
Executing the above script in MySQL workbench against the “myflixdb” produces the following results. 




movie_id
title
director
year_released
category_id






2
Forgetting Sarah Marshal
Nicholas Stoller
2008
2

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WHERE clause combined with – OR LOGICAL Operator

The WHERE clause when used together with the OR operator, is only executed if any or the entire specified filter criteria is met.
The following script gets all the movies in either category 1 or category 2
SELECT * FROM `movies` WHERE `category_id` = 1 OR `category_id` = 2;
Executing the above script in MySQL workbench against the “myflixdb” produces the following results. 




movie_id
title
director
year_released
category_id






1
Pirates of the Caribean 4
Rob Marshall
2011
1




2
Forgetting Sarah Marshal
Nicholas Stoller
2008
2

WHERE clause combined with – IN Keyword

The WHERE in MySQL clause, when used together with the IN keyword only affects the rows whose values matches the list of values provided in the IN keyword. The MySQL IN statement helps to reduce number of OR clauses you may have to use.
The following MySQL WHERE IN query gives rows where membership_number is either 1 , 2 or 3
SELECT * FROM `members` WHERE `membership_number` IN (1,2,3);

Executing the above script in MySQL workbench against the “myflixdb” produces the following results.





membership_number
full_names
gender
date_of_birth
physical_address
postal_address
contct_number
email






1
Janet Jones
Female
21-07-1980
First Street Plot No 4
Private Bag
0759 253 542
janetjones@yagoo.cm




2
Janet Smith Jones
Female
23-06-1980
Melrose 123
NULL
NULL
jj@fstreet.com




3
Robert Phil
Male
12-07-1989
3rd Street 34
NULL
12345
rm@tstreet.com

WHERE clause combined with – NOT IN Keyword

The WHERE clause when used together with the NOT IN keyword DOES NOT affects the rows whose values matches the list of values provided in the NOT IN keyword.
The following query gives rows where membership_number is NOT 1 , 2 or 3
SELECT * FROM `members` WHERE `membership_number` NOT IN (1,2,3);

Executing the above script in MySQL workbench against the “myflixdb” produces the following results.





membership_number
full_names
gender
date_of_birth
physical_address
postal_address
contct_number
email






4
Gloria Williams
Female
14-02-1984
2nd Street 23
NULL
NULL
NULL

WHERE clause combined with – COMPARISON Operators

The less than (), equal to (=), not equal to () comparison operators can be used with the WHERE Clause

= Equal To

The following script gets all the female members from the members table using the equal to comparison operator.
SELECT * FROM `members` WHERE `gender` = 'Female';

Executing the above script in MySQL workbench against the “myflixdb” produces the following results.





membership_number
full_names
gender
date_of_birth
physical_address
postal_address
contct_number
email






1
Janet Jones
Female
21-07-1980
First Street Plot No 4
Private Bag
0759 253 542
janetjones@yagoo.cm




2
Janet Smith Jones
Female
23-06-1980
Melrose 123
NULL
NULL
jj@fstreet.com




4
Gloria Williams
Female
14-02-1984
2nd Street 23
NULL
NULL
NULL

> Greater than

The following script gets all the payments that are greater than 2,000 from the payments table.
SELECT * FROM `payments` WHERE `amount_paid` > 2000;
Executing the above script in MySQL workbench against the “myflixdb” produces the following results.




payment_id
membership_number
payment_date
description
amount_paid
external_reference_number






1
1
23-07-2012
Movie rental payment
2500
11




3
3
30-07-2012
Movie rental payment
6000
NULL

< > Not Equal To

The following script gets all the movies whose category id is not 1.
SELECT * FROM `movies` WHERE `category_id`<> 1;
Executing the above script in MySQL workbench against the “myflixdb” produces the following results.




movie_id
title
director
year_released
category_id






2
Forgetting Sarah Marshal
Nicholas Stoller
2008
2




5
Daddy's Little Girls
NULL
2007
8




6
Angels and Demons
NULL
2007
6




7
Davinci Code
NULL
2007
6




9
Honey mooners
John Schultz
2005
8

Summary

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

Brain Teaser

Let’s suppose that we want to get a list of rented movies that have not been returned on time 25/06/2012. We can use the SQL WHERE statement clause together with the less than comparison operator and AND logical operator to achieve that.
SELECT * FROM `movierentals` WHERE `return_date` < '2012-06-25' AND movie_returned = 0;

Executing the above script in MySQL workbench gives the following results.





reference_number
transaction_date
return_date
membership_number
movie_id
movie_returned




14
21-06-2012
24-06-2012
2
2
0

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