Shulou(Shulou.com)06/02 Report--

In this issue, the editor will bring you about how to remove weight in the MySQL database. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

Using distinct

De-duplicate the fields that need to be processed

Select distinct field name from table name

Using group by

Select * from table name group by field name

Using having

Select * from table name group by field name having field name = required

The difference between where and having

After 1.having is used for group by

2.where is used to filter queries in tables, and having is used to query in where and group results

3.having can use aggregate functions, while where cannot

The execution order of 4.having comes after where

The above is how to achieve duplication in the MySQL database shared by the editor. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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