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
I'm pretty much out of ideas on how to get this to work.I haven't really used SQL in several years so there's a lot I don't remember.
So here is what I would like to happen:
I return the rows where the Code field from table has the value 1208 AND estnumber = 1187216
Run a count on the selection, if 0 run a subquery
If >0 run a different subquery
I didn't get to the subquery part yet because I can't get this to work correctly at all. Right now I just want it to return text.
Here is the latest attempt, I'm actually using db2 but maybe we can ignore that for now and i'll work that part out later because it says the syntax isnt correct, but other validators disagree (if you dont know anything about db2 just use standard sql when giving advice)
SELECT
count(*) AS t
FROM
table
WHERE
(
ESTNUMBER = 1187216
AND CODE = 1208
)
AND CASE WHEN t = 0 THEN 'it is zero' ELSE 'it is not zero' END;
Are you trying to do something like this?
WITH c AS (
SELECT count(*) AS cnt
FROM table
WHERE ESTNUMBER = 1187216 AND CODE = 1208
)
SELECT s1.*
FROM subquery1 s1
WHERE (SELECT cnt FROM c) = 0
UNION ALL
SELECT s2.*
FROM subquery2 s2
WHERE (SELECT cnt FROM c) > 0;
This assumes that the columns returned by the subqueries are compatible (same number, same types).
There are better ways to write this query (notably using EXISTS and NOT EXISTS), but this conforms directly to how you asked the question.
The string value should come up in the select clause and not in the where filter.
SELECT
count(*) AS t,
(CASE WHEN count(*) = 0 THEN 'it is zero' ELSE 'it is not zero' END) display_str
FROM
table
WHERE
(
ESTNUMBER = 1187216
AND CODE = 1208
)
You're thinking like an imperative programmer, not a declarative one. That is, SQL doesn't have sequential execution: it's all or nothing.
So, here's the start, the bit that works:
SELECT count(*) AS t
FROM table
WHERE ESTNUMBER = 1187216 AND CODE = 1208
Now, to check for the value of count(*), you by now know that WHERE isn't going to work. That's because COUNT is an aggregate function. To look at the result of such of function, you use HAVING.
For your CASE to work, you can move it up into the area that can get count(*) results:
SELECT count(*) AS t
(CASE WHEN count(*) = 0 THEN 'it is zero' ELSE 'it is not zero' END) as msg
FROM table
WHERE ESTNUMBER = 1187216 AND CODE = 1208
Note that "t" is an alias you've given the result of count(*). In most SQL implementations, that alias can't be leveraged in the rest of the statement.
Now, for the either or kind of thing, it would be time to reconsider your approach and what you're really after. You'll probably ultimately have both result sets in your statement and choose how the results are served up.
Something like:
select a.id, a.ct, (case when a.ct=0 then b.amt else c.amt end) as amt
from (select id, count(*) as ct from table1) a
left join (select id, sum(amount) as amt from table2) b on a.id=b.id
left join (select id, sum(amount) as amt from table3) c on a.id=c.id
Hope this helps.
I have two sql queries.
SELECT
DATE_FIRST_TABLE
FROM
FIRST_TABLE
and
SELECT
DATE_SECOND_TABLE
FROM
SECOND_TABLE
The above two queries may return single or multiple records.
I need to check the second query results if any date value is greater than any of the date value of first query results then it will evaluate true.
I need some suggestion on this.
Thanks.
Is this what you want?
select 'true'
from second_table
where date_second_table > (select max(date_first_table) from first_table)
The statement: "I need to check the second query results if any date value is greater than any of the date value of first query results then it will evaluate true." This is a bit hard to follow the logic. The above returns 'true' when the values of the second query are greater than all the values of the first query.
The answer may be:
select max('true')
from second_table
where date_second_table > (select min(date_first_table) from first_table)
A key addition is the max() function, which turns this into an aggregation function so it returns one row.
EDIT:
Your question is ambiguous about what to do in the "false" case. One answer, as you suggest in the comments is:
select (case when count(*) > 0 then 1 else 0 end)
from second_table
where date_second_table > (select min(date_first_table) from first_table);
A similar approach is to use an explicit join. Although this would perform less well, it may better capture the logic:
select (case when count(*) > 0 then 1 else 0 end)
from first_table t1 join
second_table t2
on t1.date_first_table > t2.date_second_table;
SELECT DATE_SECOND_TABLE FROM SECOND_TABLE WHERE DATE_SECOND_TABLE > (SELECT DATE_FIRST_TABLE FROM FIRST_TABLE)
When you say "it will evaluate to true", you do mean it will return the result presumably
I want to return multiple values from a query in oracle. For ex:
select count(*)
from tablename a
where asofdate='10-nov-2009'
and a.FILENAME in (case
when 1 = 1 then (select distinct filename from tablename
where asofdate='10-nov-2009' and isin is null)
else null
end);
I am getting error: ora 01427 single row subquery returns more than one row
Please advice.
Thanks, Deepak
A CASE statement cannot return more than one value, it is a function working on one value.
It is not required for your statement, this statement should work:
select count(*)
from tablename a
where asofdate='10-nov-2009'
and a.FILENAME in (select distinct filename
from tablename
where asofdate='10-nov-2009'
and isin is null);
Maybe you have another usage scenario in mind? Something like this:
Select *
From aTable
Where in CASE
WHEN Then
WHEN Then
ELSE END
Then using CASE may not be the right scenario. Maybe this helps you in the right direction:
Select *
From aTable
Where <Case1> and column1 in <Subselect1>
Or <Case2> and column1 in <Subselect2>
OR Not (<Case1> Or <Case2>) and column1 in <Subselect3>
But this will probably be quite some work for the optimizer ...
The distinct in your Case statement is attempting to return multiple values when only one is allowed, and your SELECT statement will only return one value in one row currently. If you're trying to get the count of each filename, do
SELECT FileName, Count(*)
FROM tablename
WHERE asofdate='10-nov-2009' and isin is null
GROUP BY FileName
Run this query:
select distinct filename from tablename
where asofdate='10-nov-2009' and isin is null
You'll see that it returns more than a single row which causes the ORA-01427.
For all I can tell, you're looking for something like:
select a.filename, count(*)
from tablename a
where a.asofdate = '10-nov-2009'
and exists (
select *
from tablename b
where b.isin is null
and a.asofdate = '10-nov-2009'
and a.filename = b.filename
)
group by a.filename
This would find the count of filenames for a day, for which there exists at least one row where isin is null.
If you edit your question and add an explanation of what you're looking for, you might get better answers.
I have a table
create table us
(
a number
);
Now I have data like:
a
1
2
3
4
null
null
null
8
9
Now I need a single query to count null and not null values in column a
This works for Oracle and SQL Server (you might be able to get it to work on another RDBMS):
select sum(case when a is null then 1 else 0 end) count_nulls
, count(a) count_not_nulls
from us;
Or:
select count(*) - count(a), count(a) from us;
If I understood correctly you want to count all NULL and all NOT NULL in a column...
If that is correct:
SELECT count(*) FROM us WHERE a IS NULL
UNION ALL
SELECT count(*) FROM us WHERE a IS NOT NULL
Edited to have the full query, after reading the comments :]
SELECT COUNT(*), 'null_tally' AS narrative
FROM us
WHERE a IS NULL
UNION
SELECT COUNT(*), 'not_null_tally' AS narrative
FROM us
WHERE a IS NOT NULL;
Here is a quick and dirty version that works on Oracle :
select sum(case a when null then 1 else 0) "Null values",
sum(case a when null then 0 else 1) "Non-null values"
from us
for non nulls
select count(a)
from us
for nulls
select count(*)
from us
minus
select count(a)
from us
Hence
SELECT COUNT(A) NOT_NULLS
FROM US
UNION
SELECT COUNT(*) - COUNT(A) NULLS
FROM US
ought to do the job
Better in that the column titles come out correct.
SELECT COUNT(A) NOT_NULL, COUNT(*) - COUNT(A) NULLS
FROM US
In some testing on my system, it costs a full table scan.
As i understood your query, You just run this script and get Total Null,Total NotNull rows,
select count(*) - count(a) as 'Null', count(a) as 'Not Null' from us;
usually i use this trick
select sum(case when a is null then 0 else 1 end) as count_notnull,
sum(case when a is null then 1 else 0 end) as count_null
from tab
group by a
Just to provide yet another alternative, Postgres 9.4+ allows applying a FILTER to aggregates:
SELECT
COUNT(*) FILTER (WHERE a IS NULL) count_nulls,
COUNT(*) FILTER (WHERE a IS NOT NULL) count_not_nulls
FROM us;
SQLFiddle: http://sqlfiddle.com/#!17/80a24/5
This is little tricky. Assume the table has just one column, then the Count(1) and Count(*) will give different values.
set nocount on
declare #table1 table (empid int)
insert #table1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(NULL),(11),(12),(NULL),(13),(14);
select * from #table1
select COUNT(1) as "COUNT(1)" from #table1
select COUNT(empid) "Count(empid)" from #table1
Query Results
As you can see in the image, The first result shows the table has 16 rows. out of which two rows are NULL. So when we use Count(*) the query engine counts the number of rows, So we got count result as 16. But in case of Count(empid) it counted the non-NULL-values in the column empid. So we got the result as 14.
so whenever we are using COUNT(Column) make sure we take care of NULL values as shown below.
select COUNT(isnull(empid,1)) from #table1
will count both NULL and Non-NULL values.
Note: Same thing applies even when the table is made up of more than one column. Count(1) will give total number of rows irrespective of NULL/Non-NULL values. Only when the column values are counted using Count(Column) we need to take care of NULL values.
I had a similar issue: to count all distinct values, counting null values as 1, too. A simple count doesn't work in this case, as it does not take null values into account.
Here's a snippet that works on SQL and does not involve selection of new values.
Basically, once performed the distinct, also return the row number in a new column (n) using the row_number() function, then perform a count on that column:
SELECT COUNT(n)
FROM (
SELECT *, row_number() OVER (ORDER BY [MyColumn] ASC) n
FROM (
SELECT DISTINCT [MyColumn]
FROM [MyTable]
) items
) distinctItems
Try this..
SELECT CASE
WHEN a IS NULL THEN 'Null'
ELSE 'Not Null'
END a,
Count(1)
FROM us
GROUP BY CASE
WHEN a IS NULL THEN 'Null'
ELSE 'Not Null'
END
Here are two solutions:
Select count(columnname) as countofNotNulls, count(isnull(columnname,1))-count(columnname) AS Countofnulls from table name
OR
Select count(columnname) as countofNotNulls, count(*)-count(columnname) AS Countofnulls from table name
Try
SELECT
SUM(ISNULL(a)) AS all_null,
SUM(!ISNULL(a)) AS all_not_null
FROM us;
Simple!
If you're using MS Sql Server...
SELECT COUNT(0) AS 'Null_ColumnA_Records',
(
SELECT COUNT(0)
FROM your_table
WHERE ColumnA IS NOT NULL
) AS 'NOT_Null_ColumnA_Records'
FROM your_table
WHERE ColumnA IS NULL;
I don't recomend you doing this... but here you have it (in the same table as result)
use ISNULL embedded function.
All the answers are either wrong or extremely out of date.
The simple and correct way of doing this query is using COUNT_IF function.
SELECT
COUNT_IF(a IS NULL) AS nulls,
COUNT_IF(a IS NOT NULL) AS not_nulls
FROM
us
SELECT SUM(NULLs) AS 'NULLS', SUM(NOTNULLs) AS 'NOTNULLs' FROM
(select count(*) AS 'NULLs', 0 as 'NOTNULLs' FROM us WHERE a is null
UNION select 0 as 'NULLs', count(*) AS 'NOTNULLs' FROM us WHERE a is not null) AS x
It's fugly, but it will return a single record with 2 cols indicating the count of nulls vs non nulls.
This works in T-SQL. If you're just counting the number of something and you want to include the nulls, use COALESCE instead of case.
IF OBJECT_ID('tempdb..#us') IS NOT NULL
DROP TABLE #us
CREATE TABLE #us
(
a INT NULL
);
INSERT INTO #us VALUES (1),(2),(3),(4),(NULL),(NULL),(NULL),(8),(9)
SELECT * FROM #us
SELECT CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END AS 'NULL?',
COUNT(CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END) AS 'Count'
FROM #us
GROUP BY CASE WHEN a IS NULL THEN 'NULL' ELSE 'NON-NULL' END
SELECT COALESCE(CAST(a AS NVARCHAR),'NULL') AS a,
COUNT(COALESCE(CAST(a AS NVARCHAR),'NULL')) AS 'Count'
FROM #us
GROUP BY COALESCE(CAST(a AS NVARCHAR),'NULL')
Building off of Alberto, I added the rollup.
SELECT [Narrative] = CASE
WHEN [Narrative] IS NULL THEN 'count_total' ELSE [Narrative] END
,[Count]=SUM([Count]) FROM (SELECT COUNT(*) [Count], 'count_nulls' AS [Narrative]
FROM [CrmDW].[CRM].[User]
WHERE [EmployeeID] IS NULL
UNION
SELECT COUNT(*), 'count_not_nulls ' AS narrative
FROM [CrmDW].[CRM].[User]
WHERE [EmployeeID] IS NOT NULL) S
GROUP BY [Narrative] WITH CUBE;
SELECT
ALL_VALUES
,COUNT(ALL_VALUES)
FROM(
SELECT
NVL2(A,'NOT NULL','NULL') AS ALL_VALUES
,NVL(A,0)
FROM US
)
GROUP BY ALL_VALUES
select count(isnull(NullableColumn,-1))
if its mysql, you can try something like this.
select
(select count(*) from TABLENAME WHERE a = 'null') as total_null,
(select count(*) from TABLENAME WHERE a != 'null') as total_not_null
FROM TABLENAME
Just in case you wanted it in a single record:
select
(select count(*) from tbl where colName is null) Nulls,
(select count(*) from tbl where colName is not null) NonNulls
;-)
for counting not null values
select count(*) from us where a is not null;
for counting null values
select count(*) from us where a is null;
I created the table in postgres 10 and both of the following worked:
select count(*) from us
and
select count(a is null) from us
In my case I wanted the "null distribution" amongst multiple columns:
SELECT
(CASE WHEN a IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS a_null,
(CASE WHEN b IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS b_null,
(CASE WHEN c IS NULL THEN 'NULL' ELSE 'NOT-NULL' END) AS c_null,
...
count(*)
FROM us
GROUP BY 1, 2, 3,...
ORDER BY 1, 2, 3,...
As per the '...' it is easily extendable to more columns, as many as needed
Number of elements where a is null:
select count(a) from us where a is null;
Number of elements where a is not null:
select count(a) from us where a is not null;