插入查询，表中不需要相同的数据. [英] insert query, same data not want in table.

问题描述

大家好，

当我插入数据时，
如果表中有相同的数据，则我想报错味精.
我该怎么做.

hi folks,

when i insert data,
if the same data is in the table then i want error msg.
how can i do these.

推荐答案

这实际上取决于您认为重复"的数据.

如果只有一个字段不能重复，则需要将该字段设置为主键.

如果您有两个或三个这样的字段，请创建一个复合主键.

然后，当您尝试输入重复的值时.数据库将自动生成错误消息.

It really depends upon what you consider ''duplicate'' data.

If you have just one field that should not be a duplicate what you need to do is to set that field as a primary key.

If you have two or three fields like this, create a composite primary key.

Then when you try to enter duplicate values. the database will automatically generate error messages.

您需要自行处理.在插入数据之前，请查询是否存在准确的数据，如果找到匹配项，则需要返回错误，否则可以插入数据.

You need to handle that on your own. Before you insert the data, query if exact data exist, if you found a match then you need to return an error, else you are good to insert the data.

直到我了解您的问题是，您不想在表中重复输入吗?

如果是这样，则对列使用唯一约束.

till what I understood from your problem, is u don''t want duplicate entry in your table.

If so then use unique constraint on a column.

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