What does % represent in mysql

The percent symbol % in MySQL is a wildcard character used to match any number of characters in a string. It can be placed at the beginning, end, or middle to find strings that contain, begin, or end the specified character pattern. In addition to %, MySQL supports other wildcard characters such as underscore _ and square brackets [set].

The meaning of % in MySQL

In MySQL, the % symbol represents a wildcard character, which is used in strings Matches any number of characters.

Usage of wildcard characters

% symbol can be placed at the beginning, end, or middle of a string query to match various character patterns:

• Matches starting with: %keyword matches any string starting with "keyword".
• End match: keyword% matches any string ending with "keyword".
• Intermediate matching: %keyword% matches any string containing "keyword".

Example

Here are some examples of MySQL queries using the % wildcard:

• Find the query containing All user names for "John":

  <code class="sql">SELECT username FROM users WHERE username LIKE '%John%';</code>

• Find all tables starting with "admin":

  <code class="sql">SHOW TABLES LIKE 'admin%';</code>

• Find all fields that contain "customer" but end with "cust":

  <code class="sql">SELECT column_name FROM information_schema.columns WHERE column_name LIKE '%customer' AND column_name LIKE 'cust%';</code>

Other wildcards

In addition to %, MySQL also supports other wildcard characters:

• _: The underscore matches a single character.
• [set]: Square brackets match any character in the specified character set (for example, [a-z] matches all lowercase letters).

Notes

• % Wildcard characters may cause query performance degradation, so they should be used with caution.
• Case Sensitive: MySQL wildcards are case sensitive, which means that %keyword and %KEYWORD will not match the same results.
• Escape characters: If you need to search for actual % characters in the query, use the escape character \, for example \%keyword.

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