MySQL grouped data

Group understanding grouping can be seen in the following example, first we print out the Products table as follows

As can be seen from the table above, each vendor has a number of products, then how to count how many products per vendor at a time? Here you can use GROUP by, as follows

If you do not use GROUP BY, the result is how many rows are counted:

Packet filter Packet filtering is also a multi-statistic data and then filtered, as the above example, the statistics out of each vendor has a number of products, then you can use having to filter out the number of products more than 3 vendor:


The WHERE statement can drink the having statement together with the spirit and use, if need to find out, there are more than 2 kinds of product price greater than 10: