SQL having clause discovery

The tutorials on SQL having clauses are in the following format:

 
1 SelectColumn_name, aggregate_function (column_name)
2 FromTable_name
3 WhereColumn_name operator Value
4 Group ByColumn_name
5 HavingAggregate_function (column_name) operator Value
 

This column is above w3school, link: http://www.w3school.com.cn/ SQL/SQL _having.asp

The aggregate function after having must be an aggregate function after select.

 

However, in SQL Server 2008, I do the following:

1 SelectColumn_name
2 FromTable_name
3 WhereColumn_name operator Value
4 Group ByColumn_name
5 HavingAggregate_function (column_name) operator Value
 

This means that no aggregate function is used after select, but having is used.

No error is reported, and it seems that the correct results can be returned. I wonder if you have encountered a similar situation?

My mailbox tobethe2th@gmail.com welcome to discuss.

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"Answers on sunny days" on csdn ":

"Not necessarily.
A prerequisite for having is that a group by clause can be used to set the range of aggregate function values, regardless of whether the group is queried or not ."