I'm looking for a way to build case statements in a sql select query using less than and greater than signs. For example, I want to select a ranking based on a variable:
DECLARE #a INT
SET #a = 0
SELECT CASE
WHEN #a < 3 THEN 0
WHEN #a = 3 THEN 1
WHEN #a > 3 THEN 2
END
I'd like to write it as:
DECLARE #a INT
SET #a = 0
SELECT CASE #a
WHEN < 3 THEN 0
WHEN 3 THEN 1
WHEN > 3 THEN 2
END
...but SQL doesn't let me use the < and > signs in this way. Is there a way that I can do this is SQL 2005, or do I need to use the code like in the first one.
The reason for only wanting the code there once is because it would make the code a lot more readable/maintainable and also because I'm not sure if SQL server will have to run the calculation for each CASE statement.
I'm looking for a VB.NET case statement equivelent:
Select Case i
Case Is < 100
p = 1
Case Is >= 100
p = 2
End Select
Maybe it's not possible in SQL and that's ok, I just want to confirm that.
You can use the SIGN function as
DECLARE #a INT
SET #a = 0
SELECT CASE SIGN(#a - 3)
WHEN -1 THEN 0
WHEN 0 THEN 1
WHEN 1 THEN 2
END
If #a is smaller than 3, then #a - 3 results in a negative int, in which SIGN returns -1.
If #a is 3 or greater, then SIGN returns 0 or 1, respectively.
If the output you want is 0, 1 and 2, then you can simplify even more:
DECLARE #a INT
SET #a = 0
SELECT SIGN(#a - 3) + 1
Using SIGN as suggested by #Jose Rui Santos seems a nice workaround. An alternative could be to assign the expression an alias, use a subselect and test the expression (using its alias) in the outer select:
SELECT
…,
CASE
WHEN expr < 3 THEN …
WHEN expr > 3 THEN …
END AS …
FROM (
SELECT
…,
a complex expression AS expr
FROM …
…
)
SELECT
CASE
WHEN ColumnName >=1 and ColumnName <=1 THEN 'Fail'
WHEN ColumnName >=6 THEN 'Pass'
ELSE 'Test'
END
FROM TableName
Related
DECLARE #a int
SET #a = 5
SET #a = CASE
WHEN #a >= 5 THEN 1
WHEN #a <= 5 THEN 2
WHEN a < 10 THEN 3
END
SELECT #a
#a value should be 3, but why it is showing 1?
Can anyone explain how it works?
I have been asked same question one of SQL interview
Case expression will Evaluates, as order you specified :
So, you want prioritized when clause :
case when #a < 10 then 3
when #a <= 5 then 2
when #a >= 5 then 1
end
The CASE statement goes through conditions and returns a value when the first condition is met. Following two way of your problem should be solved, you can try one of them.
declare #a int
set #a=5
set #a= case when #a>5 then 1
when #a<5 then 2
when #a <10 then 3 end
select #a
set #a=5
set #a= case when #a <10 then 3
when #a>=5 then 1
when #a<=5 then 2 end
select #a
I have a table with flag 0 and 1.
Please tell me how to update Zero to One and One to Zero
DECLARE #a INT, #b INT
SELECT #a = number
FROM zerone
WHERE number = 0
SELECT #b = number
FROM zerone
WHERE number = 1
BEGIN
IF #a = 0
UPDATE zerone
SET number = 1
WHERE #a = 0
ELSE IF #b = 1
UPDATE zerone
SET number = 0
WHERE #b = 1
END
This query is not working for me.
use the below query to update 0 to 1 and 1 to 0
update zerone set number= 1-number
Just this:
UPDATE zerone
SET number = CASE WHEN number = 1 THEN 0 ELSE 1 END;
you should also always consider NULL values in update operations and must explicitly filter them out
UPDATE zerone
SET number= case
when 1 then 0
when 0 then 1
end
WHERE number in (0,1)
Also your query will not work because you are assigning a single variable with a rows of data in the select statement.
SELECT #a = number
FROM zerone
WHERE number = 0
This does not work like as you are expecting and will only assign #a with value either NULL(if there are no rows) or with 0 if there is a row. If there are multiple rows even then it will have a single value 0
As you have seen there are so many ways to perform that task but in this case, I would prefer #Abdul Rasheed.
We can also use below IIF logical function in SQLSERVER2012 or above.
UPDATE zerone
SET number = IIF (number = 1, 0, 1)
I want to get multipule choises after then in case statment as
#value
select * from [dbo].[Currency_Tbl]
WHERE [Currency_Active_YN]=
CASE WHEN #value = 1 THEN
( 1 or 0)
ELSE
#Value = 0 then 0
END
it didn't accept the first line in col1 but accept the col2
how can I select multiple numbers after THEN?
You don't use case in where clauses. Use boolean logic
select * from [dbo].[Currency_Tbl]
WHERE (#value = 1 and [Currency_Active_YN] in (0,1))
OR (#value = 0 and [Currency_Active_YN] = 0)
You dont need a case to do what you're trying to do. Assuming Currency_Active_YN is a not null bit field the following logic should suffice.
select * from [dbo].[Currency_Tbl]
WHERE (#value=1 OR [Currency_Active_YN]=#Value)
Not sure is this the right title. I need to find the cumulative multiplication as like running total.
Searched the forum and got a excellent answer. But it is not the exact answer for me.
so modified the answer to my requirement.
SELECT *,
(SELECT CASE
WHEN Min(Abs(Column1)) = 0 THEN 0
ELSE Exp(Sum(Log(Abs(NULLIF(Column1, 0))))) -- the base mathematics
* Round(0.5 - Count(NULLIF(Sign(Sign(Column1) + 0.5), 1))%2, 0) -- pairs up negatives
END
FROM TEMP a
WHERE B.ID >= A.ID) as Running_Mul
FROM TEMP B
And I got my answer. Now Is there any better way of doing this in Sql Server 2008?
Sample data:
ID Column1
-- -------
1 1
2 2
3 4
4 8
5 -2
Expected Result:
ID Column1 Running_Mul
-- ------- -----------
1 1 1
2 2 2
3 4 8
4 8 64
5 -2 -128
Sql Fiddle
Your method is pretty reasonable. Good catch on the nullif() in the sum(), by the way. Although the else clause is computed only after the then, components of the else are calculated during the aggregation -- so log(0) would return an error.
I think there are some simpler ways to calculate the sign, such as:
power(-1, sum(case when column1 < 0 then 1 else 0 end))
or:
(case when sum(case when column1 < 0 then 1 else 0 end) % 2 = 0 then 1 else -1 end)
However, which version is "simpler" is a matter of opinion.
Here is another approach which I use in my SPs :
USE DB
GO
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
GO
IF(OBJECT_ID('TEMP') IS NOT NULL)
DROP TABLE TEMP
CREATE TABLE TEMP (ID INT, Column1 INT)
INSERT INTO TEMP VALUES
(1,1),
(2,2),
(3,4),
(4,8),
(5,-2)
DECLARE #result TABLE(ID INT, Column1 INT, calc INT)
DECLARE #Calc INT = 1
INSERT INTO #result (ID,Column1)
SELECT ID,Column1 FROM TEMP ORDER BY ID
UPDATE #result SET #Calc = calc = Column1 * #Calc
SELECT * FROM #result
I found a blog in which different methods to solve such problem, have been compared. check here.
How to know if all the cells have the same value in some column (title changed)
I want to have a bit scalar value that tells me if all the values in a column equal something:
DECLARE #bit bit
SELECT #bit = TRUEFORALL(Name IS NOT NULL) FROM Contact
UPDATE
I now realized that I actually don't need the TrueForAll, what I do need is to make sure, that all values in a column are equal, for example, I want to know whether all Group.Items have the same price.
Why not?
select count( distinct price) from table
If returns 1, all values are the same... Add
where price is not null
if need be
For your updated requirement something like this would appear to do what you want:
DECLARE #IsSameGroup bit
SELECT #IsSameGroup = CASE WHEN COUNT(*) > 1 THEN 0 ELSE 1 END
FROM (SELECT Name FROM Contact GROUP BY Name) groups
When the count is greater the 1 you have two different names (or prices depending on what you group on)
Not very good for NULLs, but 2008 can do:
SELECT 1 WHERE 'Blue' = ALL ( SELECT Color FROM dbo.Hat )
OR
DECLARE #bit bit
SET #bit =
CASE ( SELECT 1 WHERE 'Blue' = ALL ( SELECT Color FROM dbo.Hat ))
WHEN 1 THEN 1 ELSE 0 END
UPDATE
All same color
SET #bit =
CASE(
SELECT 1 WHERE
(SELECT TOP(1) Color FROM dbo.Hat) = ALL ( SELECT Color FROM dbo.Hat )
)
WHEN 1 THEN 1 ELSE 0 END
Maybe this?
DECLARE #bit bit
if exists(SELECT Name FROM Contact WHERE Name IS NULL)
SET #bit = 0
ELSE
SET #bit = 1
This solves your first question:
SELECT
CASE
WHEN EXISTS(
SELECT 1
FROM Contact
WHERE Name IS NULL
) THEN 0
ELSE 1
END
ADDED:
This will solve your second:
SELECT
CASE
WHEN EXISTS(
SELECT TOP 1 1 FROM (
SELECT
ItemGroupName,
COUNT(Price) AS CNT
FROM ItemGroup
GROUP BY ItemGroupName
HAVING COUNT(Price) > 1
) t
) THEN 0
ELSE 1
END
By the way, when you use the exists function, its better to SELECT 1 (a constant) so less data gets returned