According to the statistics of the article number of the SQL client order
The order table how to implement

CodePudding user response:

Table link more, group by group, the basic idea is this

CodePudding user response:

The ORDER table is how to create

CodePudding user response:

This left right connections to is like this

CodePudding user response:

This simple order according to the customer table or table has been left links to the rest of the table
Then the sum (case when then end) group