如何解决SQL SELECT语句不适用于DELETE
我有一条sql语句,试图运行该语句以删除与user_id和用户名关联的答案。该查询在尝试选择时有效,但不适用于删除。我在DELETE语句上遇到的错误如下:
You have an error in your sql Syntax; check the manual that corresponds to your MariaDB server version for the right Syntax to use near 'AS ans INNER JOIN users AS usr ON ans.user_id = usr.user_id WHERE (usr.userna...' at line 1
Query is: DELETE FROM answers AS ans INNER JOIN users AS usr ON ans.user_id = usr.user_id WHERE (usr.username = 'antonios')
我从SELECT语句获得的输出:
1 answer text goes here 1 1 a 12 44 44 antonios U4HhMNnasQB1919QduzHO9+tgWoxsfqMY4MDUwYDDqQ= $argon2id$v=19$m=125000,t=4,p=1$gE6rtZdzpBaehzlyrVreRQ$WuhSeAaXE2bX3N4/k1yu3yQm9p7UdKGeCU/vmYn+M7c 0 0 0 0 0 2020-10-14
SELECT语句:
SELECT * FROM answers AS ans INNER JOIN users AS usr ON ans.user_id = usr.user_id WHERE (usr.username = 'username');
DELETE语句:
DELETE FROM answers AS ans INNER JOIN users AS usr ON ans.user_id = usr.user_id WHERE (usr.username = 'username');
users
的表结构:
user_id int(11) NO PRIMARY_KEY auto_increment
username varchar(40) NOT_NULL MUL_KEY
email varchar(128) NOT_NULL
password char(98) NOT_NULL
userscore int(10) unsigned NOT_NULL DEFAULT: 0
questionsAnswered int(10) unsigned NOT_NULL DEFAULT: 0
highestAnswerStreak int(10) unsigned NOT_NULL DEFAULT: 0
correctAnswers int(10) unsigned NOT_NULL DEFAULT: 0
wrongAnswers int(10) unsigned NOT_NULL DEFAULT: 0
activeSince date NOT_NULL
answers
的表结构:
answers_id int(11) NOT_NULL PRIMARY_KEY auto_increment
answerText text NOT_NULL
question_id int(11) NOT_NULL
isCorrect tinyint(4) NOT_NULL
choiceLetter varchar(1) NOT_NULL
questionNumber smallint(6) NOT_NULL
user_id int(11) NOT_NULL
通过删除,DELETE语句的预期输出将影响answers
表中的一行或多行(分配给从user_id中的用户名获得的user_id的所有行)。
解决方法
您很近。您需要列出要删除的表。例如:
DELETE ans
FROM answers ans INNER JOIN
users usr
ON ans.user_id = usr.user_id
WHERE usr.username = 'username';
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