本文介绍了SQL键，MUL，PRI和UNI的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
在MySQL中MUL，PRI和UNI有什么区别?
What is the difference between MUL, PRI and UNI in MySQL?
我正在使用以下命令处理MySQL查询:
I'm working on a MySQL query, using the command:
desc mytable;
其中一个字段显示为MUL键，其他字段显示为UNI或PRI.
One of the fields is shown as being a MUL key, others show up as UNI or PRI.
我知道，如果键为PRI，则每个表只能将一个记录与该键关联.如果键为MUL，是否表示可能有多个相关记录?
I know that if a key is PRI, only one record per table can be associated with that key. If a key is MUL, does that mean that there could be more than one associated record?
这是mytable的响应.
+-----------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+-------+
| courseid | int(11) | YES | MUL | NULL | |
| dept | char(3) | YES | | NULL | |
| coursenum | char(4) | YES | | NULL | |
+-----------+---------+------+-----+---------+-------+
推荐答案
这意味着该字段是非唯一索引(的一部分).您可以发出
It means that the field is (part of) a non-unique index. You can issue
show create table <table>;
查看有关表结构的更多信息.
To see more information about the table structure.
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