SELECT logcount, logUserID, maxlogtm
, DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
FROM statslogsummary
WHERE daysdiff > 120
I get
"invalid column name daysdiff".
Maxlogtm is a datetime field. It's the little stuff that drives me crazy.
This question is related to
sql
sql-server
tsql
sql-server-2005
For me, the simplest way to use ALIAS in WHERE class is to create a subquery and select from it instead.
Example:
WITH Q1 AS (
SELECT LENGTH(name) AS name_length,
id,
name
FROM any_table
)
SELECT id, name, name_length form Q1 where name_length > 0
Cheers, Kel
If you want to use the alias in your WHERE
clause, you need to wrap it in a sub select, or CTE:
WITH LogDateDiff AS
(
SELECT logcount, logUserID, maxlogtm
, DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
FROM statslogsummary
)
SELECT logCount, logUserId, maxlogtm, daysdiff
FROM LogDateDiff
WHERE daysdiff > 120
Came here looking something similar to that, but with a CASE WHEN, and ended using the where like this: WHERE (CASE WHEN COLUMN1=COLUMN2 THEN '1' ELSE '0' END) = 0
maybe you could use DATEDIFF
in the WHERE
directly.
Something like:
SELECT logcount, logUserID, maxlogtm
FROM statslogsummary
WHERE (DATEDIFF(day, maxlogtm, GETDATE())) > 120
How about using a subquery(this worked for me in Mysql)?
SELECT * from (SELECT logcount, logUserID, maxlogtm
, DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
FROM statslogsummary) as 'your_alias'
WHERE daysdiff > 120
The most effective way to do it without repeating your code is use of HAVING instead of WHERE
SELECT logcount, logUserID, maxlogtm
, DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
FROM statslogsummary
HAVING daysdiff > 120
You could refer to column alias but you need to define it using CROSS/OUTER APPLY
:
SELECT s.logcount, s.logUserID, s.maxlogtm, c.daysdiff
FROM statslogsummary s
CROSS APPLY (SELECT DATEDIFF(day, s.maxlogtm, GETDATE()) AS daysdiff) c
WHERE c.daysdiff > 120;
Pros:
WHERE/GROUP BY/ORDER BY
HAVING works in MySQL according to documentation:
The HAVING clause was added to SQL because the WHERE keyword could not be used with aggregate functions.
If you don't want to list all your columns in CTE, another way to do this would be to use outer apply
:
select
s.logcount, s.logUserID, s.maxlogtm,
a.daysdiff
from statslogsummary as s
outer apply (select datediff(day, s.maxlogtm, getdate()) as daysdiff) as a
where a.daysdiff > 120
Source: Stackoverflow.com