Check if a user exists in MySQL.

You can use the following MySQL query statement to check if a user exists:

SELECT EXISTS(SELECT 1 FROM 用户表 WHERE 用户名 = '要查询的用户名') AS 用户存在与否;

Please replace the user table in the query statement with the actual name of your user table, and replace the username with the username you want to query. Running this query will return a boolean value, 1 if the user exists and 0 if the user does not exist.

To check if a specific user exists, you can modify the query statement.

SELECT EXISTS(SELECT 1 FROM 用户表 WHERE 用户名 = '要查询的用户名') AS 用户存在与否;

Similarly, replace the user table with the actual name of your user table and the username with the username you want to query. Executing this query will return a boolean value of 1 if the user exists and 0 if the user does not exist.