SQL Tickets sold - Last 30 Days - use Where or Having?-CodePudding

How many tickets were sold for each route and each day, for the routes sold in the last 30 days from current day?

SELECT COUNT(TICKET_ID) NUMBER_TICKETS, ROUTE_CODE, FLIGHT_DATE 
FROM TICKETS 
WHERE (DAYS(CURRENT DATE)- DAYS(FLIGHT_DATE))<=30
GROUP BY ROUTE_CODE, FLIGHT_DATE

Should this be WHERE or HAVING? I am not sure which way is correct?

CodePudding user response：

You want it in the WHERE.

Here is the best way to understand this --

The WHERE clause is used before the GROUP BY

The HAVING clause is used after the GROUP BY

So -- you want to group items in the last 30 days -- that happens before the group.

CodePudding user response：

where is the right command, consider to use "datediff" for calculate 30 days

CodePudding user response：

the WHERE clause is used to specify a condition for filtering records before any groupings are made the HAVING clause is used to specify a condition for filtering values from a group

in this case, the where clause is used for filtering the condition, not the group. You should use "having",for example, if you wanted to check the ticket_id.