Detailed use cases of MySql escape

MySQL escape

Escape means the original semantics of the escape character. The purpose of an escape character is to start a character sequence so that the character sequence starting with the escape character has different semantics than when the character sequence appears alone.

In the SQL LIKE statement, for example

select * from user where username like '%nihao%'，select * from user where username like '_nihao',

Among them, % is used as a wildcard to match multiple characters, and _ is used as a wildcard to match only one character.

If you really want to search for usernames that contain % _ , you need to stop using them as wildcards.

Escape % _ in like, take _ as an example,

Before escaping: select * from user where username like '_nihao',

After escaping: select * from user where username like '/_nihao' escape '/', which means that the _ after / is not used as a wildcard

#Case 3: Query the employee names whose second character is _

SELECT
    last_name
FROM
    employees
WHERE
    last_name LIKE '_$_%' ESCAPE '$';

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