SQL Wildcard Operations

Explanation

A wildcard is used to replace one or more characters in a string.

Wildcards are useful in situations when incomplete information is available and it would be impossible to write a WHERE clause using one of the existing logical operators =, <, >, ≤ or ≥.

Wildcard characters are used with the SQL LIKE operator. The LIKE operator is used in a WHERE clause to perform search operations.

Two different wildcards can be used:

% (percentage synbol) is used to represent zero, one or multiple characters - (a dash) is used to represent a single character

The following are some examples of LIKE used with the wildcards:

Example	Purpose
WHERE surname LIKE `Thom%`	Used to find any values in the surname field that start with `Thom`
WHERE surname LIKE `%son`	Used to find any values in the surname field that end with `son`
WHERE surname LIKE `%is%`	Used to find any values that have `is` anywhere in the surname field
WHERE surname LIKE `_h%`	Used to find any values in the surname field that have `h` as the second character
WHERE surname LIKE `m__`	Used to find any values in the surname field that start with `m` and have at least 3 characters
WHERE surname LIKE `a%z`	Used to find any values in the surname field that that start with `a` and end with `z`

Use case example:

SELECT Hotel.hotelName, Hotel.swimmingPool, Resort.resortName, Resort.resortType 
FROM Hotel, Resort 
WHERE Hotel.resortID = Resort.resortID AND resortName LIKE 'A%' AND resortType = 'coastal'; 