Question

我在堆栈中搜索，但他们都没有达到最终答案。我的疑问是：

    INSERT INTO user (username,frequence,autoSend) 
    VALUES('feri2','3','1') 
    WHERE NOT EXISTS ( SELECT * FROM user WHERE username='feri2')

运行时，我收到语法分析错误：

SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE NOT EXISTS ( SELECT * FROM user WHERE username='feri2')' at line 1

我不知道如何解决问题，问题出在哪里？

Answer 1

您需要稍微更改语法，请尝试以下操作：

INSERT INTO user (username,frequence,autoSend)
SELECT * FROM (SELECT 'feri2','3','1') AS `values`
WHERE NOT EXISTS (
    SELECT username FROM user WHERE username='feri2'
) LIMIT 1;

Answer 2

如果您不想要重复用户，则username列上可能应该有一个UNIQUE索引。如果你添加它，那么你可以简单地：

INSERT IGNORE INTO user (username,frequence,autoSend) 
VALUES('feri2','3','1')

如果已经有用户'feri2'，那么它什么都不做。

WHERE NOT EXIST附近的语法错误

2 个答案: