There is such a sentence, executing unsuccessful
SELECT Count (*) AS EXPR1 from (SELECT Visitor_ip from visitor where visitor_requesttime> 2005/03/28 ') Group by visitor_ip) DerivedTBL
Returning an error
Server: Message 156, Level 15, State 1, Row 1 There is a syntax error near the keyword 'group'.
After the change, the sentence is
Select Count (*) AS EXPR1FROM (SELECT VITOR_IP FROM (SELECT VITOR_IP FROM (SELECT VITOR_IP from Visitor Where Visitor_RequestTime> '2005/03/28') DerivedTBL Group by visitor_ip) DerivedTBL
execution succeed
Cause Analysis:
Just join the DeriveDTBL keyword as long as you perform the picking operation from the result set.
(The company's master said, the specific thing is not clear, this keyword can not be found in the online series.)
This place is clear, it is really an alias.
Thanks to the guidance of cxlfly, thank you.
