SQL - LIKE

We will use the Customers table to illustrate the LIKE clause usage:

FirstName	LastName	Email	DOB	Phone
John	Smith	John.Smith@yahoo.com	2/4/1968	626 222-2222
Steven	Goldfish	goldfish@fishhere.net	4/4/1974	323 455-4545
Paula	Brown	pb@herowndomain.org	5/24/1978	416 323-3232
James	Smith	jim@supergig.co.uk	20/10/1980	416 323-8888

The LIKE clause is very useful when you want to specify a search condition within your WHERE clause, based on a part of a column contents. For example if you want to select all customers having FirstName starting with 'J' you need to use the following SQL statement:

SELECT * FROM Customers WHERE FirstName LIKE 'J%'

Here is the result of the SQL statement above:

FirstName	LastName	Email	DOB	Phone
John	Smith	John.Smith@yahoo.com	2/4/1968	626 222-2222
James	Smith	jim@supergig.co.uk	20/10/1980	416 323-8888

If you want to select all Customers with phone numbers starting with '416' you will use this SQL expression:

SELECT * FROM Customers WHERE Phone LIKE '416%'

The '%' is a so called wildcard character and represents any string in our pattern.
You can put the wildcard anywhere in the string following the SQL LIKE clause and you can put as many wildcards as you like too.

Note that different databases use different characters as wildcard characters, for example '%' is a wildcard character for MS SQL Server representing any string, and '*' is the corresponding wildcard character used in MS Access.

Another wildcard character is '_' representing any single character.

The '[]' specifies a range of characters. Have a look at the following SQL statement:

SELECT * FROM Customers WHERE Phone LIKE '[4-6]_6%'

·         This SQL expression will return all customers satisfying the following conditions:

·         The Phone column starts with a digit between 4 and 6 ([4-6])

·         Second character in the Phone column can be anything (_)

·         The third character in the Phone column is 6 (6)

·         The remainder of the Phone column can be any character string (%)

Here is the result of this SQL expression:

FirstName	LastName	Email	DOB	Phone
John	Smith	John.Smith@yahoo.com	2/4/1968	626 222-2222
Paula	Brown	pb@herowndomain.org	5/24/1978	416 323-3232
James	Smith	jim@supergig.co.uk	20/10/1980	416 323-8888