MySQL 插入成功返回行，否则返回 'failure'

Question

我的初始插入语句工作正常，但我想将自定义结果发送回我的应用程序。这可能吗？ (请参阅下面的最后一个 SELECT 语句):

-- this is working    
INSERT INTO users (email, firstName, lastName, password)

SELECT * FROM (
    SELECT '{{email}}' as email, 
    'test' as firstName, 
    'person' as lastName, 
    '{{password}}' as password) AS tmp
WHERE NOT EXISTS (
    SELECT email FROM users WHERE email = '{{email}}'
) LIMIT 1;

-- this statement is not working.
SELECT IF(ROW_COUNT() > 0, 
    SELECT * FROM users WHERE email = '{{email}}', 
    'failure'
);

运行这个给我:

错误详情:您的 SQL 语法有误；查看与您的 MySQL 服务器版本对应的手册，了解在第 2 行的“SELECT * FROM users WHERE email = 'd@gmail.com', 'failure' )'附近使用的正确语法

Answer 1

我认为您尝试做的是:

SELECT IF(
    (SELECT COUNT(*) FROM users WHERE email = '{{email}}') > 0,
    'success',
    'false'
);