I have the below query
With max_cm1 as (select * from tableA)
Select * ,
CASE WHEN TO_CHAR(CCP2.END_DATE,'MM/DD/YYYY') <> '09/09/9000' THEN 'CLOSED'
WHEN MAX_CM1.MAX_ROLE_CM IS NOT NULL AND HIST.PCMUID IS NOT NULL THEN 'ASSIGNED'
ELSE 'UNASSIGNED'
END STATUS
from max_cm1
Now I need to filter on the case statement. How can I do this?
You can use an alias eg: m.
With max_cm1 as (select * from tableA)
Select m.* ,
CASE WHEN TO_CHAR(CCP2.END_DATE,'MM/DD/YYYY') <> '09/09/9000' THEN 'CLOSED'
WHEN MAX_CM1.MAX_ROLE_CM IS NOT NULL AND HIST.PCMUID IS NOT NULL THEN 'ASSIGNED'
ELSE 'UNASSIGNED'
END STATUS
from max_cm1 m;
In your case, you don't need a CTE unless you are joining it with other table with some expressions in CTE. Directly you can fetch from table A with the same method if you are only interested in select '*'.
Your question is unclear. Also, the query as given is somewhat confusing, as it qualifies some columns with table names (CCP2 and HIST) that don't appear elsewhere in the query. Further, as written there seems to be no purpose to the CTE at all.
I'm assuming that what you want is to include the given CASE expression in the result set, but also use it within the WHERE clause to filter the results (e.g. WHERE CASE ... END = 'CLOSED'. The simple way to do this is to repeat the CASE expression; but of course duplicating logic is never a good choice. So the better way, which I think is the point of your question, is to include that derived column in a CTE so you can then refer to it by name in the WHERE clause.
It also looks like you are probably running into the issue of trying to select all columns (*) plus a derived column. The way around this is to qualify the * with the table name, or an alias as indicated in one of the other answers.
Putting this all together, I believe you want something like the following. I'm keeping the column expressions (e.g. HIST.PCMUID) as you wrote them although as written they make no sense. I'm guessing that tableA really represents some join of multiple tables.
WITH max_cm1 AS (
SELECT tableA.* ,
CASE WHEN TO_CHAR(CCP2.END_DATE,'MM/DD/YYYY') <> '09/09/9000' THEN 'CLOSED'
WHEN MAX_CM1.MAX_ROLE_CM IS NOT NULL AND HIST.PCMUID IS NOT NULL THEN
'ASSIGNED'
ELSE 'UNASSIGNED'
END STATUS
FROM tableA
)
SELECT *
FROM max_cm1
WHERE status = 'CLOSED'
Related
I have the following SQL Query :
(SELECT ROUND(SUM(NBTOSUM)/1000000,1) FROM MyTable t2 WHERE t2.ELEMNAME IN ('A','B','C'))
Which works fine.
But Where there is no 'A','B','C' the result of the select is (null)
So to handle it, I did the following :
(SELECT COALESCE(ROUND(SUM(NBTOSUM)/1000000,1),0) FROM MyTable t2 WHERE t2.ELEMNAME IN ('A','B','C'))
And also try :
(SELECT
CASE
WHEN SUM(NBTOSUM)/1000000 IS NULL THEN 0
ELSE ROUND(SUM(NBTOSUM)/1000000,1)
END
FROM MyTable t2 WHERE t2.ELEMNAME IN ('A','B','C'))
But both keep returning null
What am I doing wrong ?
Move the WHERE restrictions to the CASE expression as well:
SELECT ROUND(SUM(CASE WHEN t2.ELEMNAME IN ('A','B','C')
THEN NBTOSUM ELSE 0 END) / 1000000, 1)
FROM MyTable t2;
Note that this trick solves the null problem and also avoids the need for an ugly COALESCE() call.
Your code should work as the SUM aggregation function will generate a single row of output regardless of whether the number of input rows is zero or non-zero. If there are no input rows or the values are all NULL then the output of the SUM will be NULL and then COALESCE would work.
Since you claim it does not then that suggests that there is something else going on in your query that you have not shared in the question.
You have braces around your statement suggesting that you are using it as part of a larger statement. If so, you can try moving the COALESCE to the outer query:
SELECT COALESCE(
(
SELECT ROUND(SUM(NBTOSUM)/1000000,1)
FROM MyTable
WHERE ELEMNAME IN ('A','B','C')
),
0
)
FROM your_outer_query;
That might fix the problem if you are somehow correlating to an outer query but your question makes no mention of that.
fiddle
This may come off as a feature request more than anything, but it would be nice if SQL allowed use of the IN operator in a select statement such as the one below. I want to create new_variable intable1based on the ID variable in table2, hence the case statement.
select ID,
case when ID in (select ID
from table2)
then 1
else 0
end as new_variable
from table1
I understand that SQL will give me an error if I run this, but why is that the case? It doesn't seem obvious to me why SQL developers couldn't enable the IN operator to be used outside of the WHERE clause.
Side note: I'm currently using a left join to avoid this issue, so I am not hung up on this.
select ID,
case when ifnull(b.ID, 0) = 0 then 0
else 1
end as variable_name
from table1
left join(select ID from table2) as b
on a.ID = b.ID
SQL definitely supports this:
select ID,
(case when ID in (select ID from table2)
then 1 else 0
end) as new_variable
from table1
Note that there is a comma after id.
This is standard SQL. If your database doesn't support it, it is a feature request (and one that all or almost all databases support).
As stated by the question, I'm trying to formulate a query that has a case statement in the column results, and then I want to include that column in the query's group by statement. To give a concrete example, here is all little of what my query looks like:
SELECT SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
ELSE 'B'
END AS CASE_COLUMN
FROM SOME_TABLE SOME_TABLE_ALIAS
... (other table joins and where clauses)
GROUP BY SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2, CASE_COLUMN
Before coming here, I checked out a few websites, including this one, to try solve my problem. I've tried adding another alias after the CASE keyword like is shown in the linked web page but have had no luck. The error message I continue to receive is the following:
[Error] Script lines: 127-151 ----------------------
CASE_COLUMN IS NOT VALID IN THE CONTEXT WHERE IT IS USED. SQLCODE=-206, SQLSTATE=42703, DRIVER=3.53.71
Has anyone else run into the issues I'm facing and been able to use a GROUP BY on the results of a CASE statement? Any help would be appreciated. Oh, and the DB2 version is a z/OS instance, version 10 (DSN10015)
The alias isn't available to use in the GROUP BY because when GROUP BY happens the alias isn't defined yet:
Here's the order:
1.FROM
2.WHERE
3.GROUP BY
4.HAVING
5.SELECT
6.ORDER BY
You can work around that with:
SELECT column1,column2,case_column
FROM (
SELECT SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
ELSE 'B'
END AS CASE_COLUMN
FROM SOME_TABLE SOME_TABLE_ALIAS
... (other table joins and where clauses)
) a
GROUP BY COLUMN1, COLUMN2, CASE_COLUMN
Or just use the case you use in SELECT in GROUP BY
You can either use the case as is in the group by, like this:
SELECT SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
ELSE 'B'
END AS CASE_COLUMN
FROM SOME_TABLE SOME_TABLE_ALIAS
... (other table joins and where clauses)
GROUP BY SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
ELSE 'B'
END
or use a sub-query like this:
select COLUMN1, COLUMN2, CASE_COLUMN
from (
SELECT SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
ELSE 'B'
END AS CASE_COLUMN
FROM SOME_TABLE SOME_TABLE_ALIAS
... (other table joins and where clauses)
) a
GROUP BY COLUMN1, COLUMN2, CASE_COLUMN
I have a table with several rows, and several columns. It looks like this:
Name Description
X PASS
X PASS
X FAIL
I want it to return only one row. If all of them are PASS, return PASS.
If one or more of them are FAIL, then return FAIL.
What's the best way to go about achieving this in SQL Server 2008?
EDIT: The values in the name column will always be the same.
Depending on the database indexes, and assuming you want one row returned per unique name, I would look at the performance of
select
name,
min([description]) as description
from
tableA
group by
name
compared to the other solutions
SELECT TOP 1 CASE Description WHEN 'FAIL' THEN 'FAIL' ELSE 'PASS' END
FROM DaTable
ORDER BY Description
OP: Is it possible that the table is empty? In that case this query won't return any rows, obviously.
EDIT
According to aquinas's comment I created a modified query without ordering:
SELECT CASE COUNT(Description) WHEN 0 THEN 'FAIL' ELSE 'PASS' END
FROM DaTable
WHERE Description = 'FAIL'
This query will return PASS if DaTable is empty.
This is the simplest solution you will find:
SELECT MIN(Description) FROM tbl
If there's at least one FAIL, then our result column will contain FAIL, otherwise, it will contain PASS.
You can use EXISTS to get the existance of a row containing "FAIL".
You could also try something like:
SELECT TOP 1 COALESCE(tFail.Description,t.Description)
FROM myTable AS t
LEFT JOIN myTable AS tFail ON tFail.Name = t.Name AND tFail.Description = 'FAIL'
WHERE t.Name = 'x'
Here is the query:
--DROP TABLE result
CREATE TABLE result(Name varchar(10),Description varchar(20))
--select * from result
INSERT INTO result
VALUES('X','PASS'),('X','PASS'),('X','FAIL')
;WITH CTE(descp,cnt) as (SELECT [description],COUNT(*) as cnt FROM result group by [description])
SELECT CASE WHEN COUNT(*) > 1 then 'FAIL' when COUNT(*)=1 then MAX(descp) else 'PASS' END FROM CTE
I have a table that has a processed_timestamp column -- if a record has been processed then that field contains the datetime it was processed, otherwise it is null.
I want to write a query that returns two rows:
NULL xx -- count of records with null timestamps
NOT NULL yy -- count of records with non-null timestamps
Is that possible?
Update: The table is quite large, so efficiency is important. I could just run two queries to calculate each total separately, but I want to avoid hitting the table twice if I can avoid it.
In MySQL you could do something like
SELECT
IF(ISNULL(processed_timestamp), 'NULL', 'NOT NULL') as myfield,
COUNT(*)
FROM mytable
GROUP BY myfield
In T-SQL (MS SQL Server), this works:
SELECT
CASE WHEN Field IS NULL THEN 'NULL' ELSE 'NOT NULL' END FieldContent,
COUNT(*) FieldCount
FROM
TheTable
GROUP BY
CASE WHEN Field IS NULL THEN 'NULL' ELSE 'NOT NULL' END
Oracle:
group by nvl2(field, 'NOT NULL', 'NULL')
Try the following, it's vendor-neutral:
select
'null ' as type,
count(*) as quant
from tbl
where tmstmp is null
union all
select
'not null' as type,
count(*) as quant
from tbl
where tmstmp is not null
After having our local DB2 guru look at this, he concurs: none of the solutions presented to date (including this one) can avoid a full table scan (of the table if timestamp is not indexed, or of the indexotherwise). They all scan every record in the table exactly once.
All the CASE/IF/NVL2() solutions do a null-to-string conversion for each row, introducing unnecessary load on the DBMS. This solution does not have that problem.
Stewart,
Maybe consider this solution. It is (also!) vendor non-specific.
SELECT count([processed_timestamp]) AS notnullrows,
count(*) - count([processed_timestamp]) AS nullrows
FROM table
As for efficiency, this avoids 2x index seeks/table scans/whatever by including the results on one row. If you absolutely require 2 rows in the result, two passes over the set may be unavoidable because of unioning aggregates.
Hope this helps
If it's oracle then you can do:
select decode(field,NULL,'NULL','NOT NULL'), count(*)
from table
group by decode(field,NULL,'NULL','NOT NULL');
I'm sure that other DBs allow for similar trick.
Another MySQL method is to use the CASE operator, which can be generalised to more alternatives than IF():
SELECT CASE WHEN processed_timestamp IS NULL THEN 'NULL'
ELSE 'NOT NULL' END AS a,
COUNT(*) AS n
FROM logs
GROUP BY a
SQL Server (starting with 2012):
SELECT IIF(ISDATE(processed_timestamp) = 0, 'NULL', 'NON NULL'), COUNT(*)
FROM MyTable
GROUP BY ISDATE(processed_timestamp);
Another way in T-sql (sql-server)
select count(case when t.timestamps is null
then 1
else null end) NULLROWS,
count(case when t.timestamps is not null
then 1
else null end) NOTNULLROWS
from myTable t
If your database has an efficient COUNT(*) function for a table, you could COUNT whichever is the smaller number, and subtract.
In Oracle
SELECT COUNT(*), COUNT(TIME_STAMP_COLUMN)
FROM TABLE;
count(*) returns the count of all rows
count(column_name) returns the number of rows which are not NULL, so
SELECT COUNT(*) - COUNT(TIME_STAMP_COLUMN) NUL_COUNT,
COUNT(TIME_STAMP_COLUMN) NON_NUL_COUNT
FROM TABLE
ought to do the job.
If the column is indexed, you might end up with some sort of range scan and avoid actually reading the table.
I personally like Pax's solution, but if you absolutely require only one row returned (as I had recently), In MS SQL Server 2005/2008 you can "stack" the two queries using a CTE
with NullRows (countOf)
AS
(
SELECT count(*)
FORM table
WHERE [processed_timestamp] IS NOT NULL
)
SELECT count(*) AS nulls, countOf
FROM table, NullRows
WHERE [processed_timestamp] IS NULL
GROUP BY countOf
Hope this helps
[T-SQL]:
select [case], count(*) tally
from (
select
case when [processed_timestamp] is null then 'null'
else 'not null'
end [case]
from myTable
) a
And you can add into the case statement whatever other values you'd like to form a partition, e.g. today, yesterday, between noon and 2pm, after 6pm on a Thursday.
Select Sum(Case When processed_timestamp IS NULL
Then 1
Else 0
End) not_processed_count,
Sum(Case When processed_timestamp Is Not NULL
Then 1
Else 0
End) processed_count,
Count(1) total
From table
Edit: didn't read carefully, this one returns a single row.