在您提供的查询中,它使用完整的外部联接。改用联合选择。
SELECT username FROM table1 WHERE username = '$username'
UNION SELECT username FROM table2 WHERE username = '$username'
UNION SELECT username FROM table3 WHERE username = '$username'
PHP:一次搜索更多表?
在您提供的查询中,它使用完整的外部联接。改用联合选择。
SELECT username FROM table1 WHERE username = '$username'
UNION SELECT username FROM table2 WHERE username = '$username'
UNION SELECT username FROM table3 WHERE username = '$username'