OK, the umpteenth conditional column question:
I'm writing a stored proc that takes an input parameter that's mapped to one of several flag columns. What's the best way to filter on the requested column? I'm currently on SQL2000, but about to move to SQL2008, so I'll take a contemporary solution if one's available.
The table queried in the sproc looks like
ID ... fooFlag barFlag bazFlag quuxFlag
-- ------- ------- ------- --------
01 1 0 0 1
02 0 1 0 0
03 0 0 1 1
04 1 0 0 0
and I want to do something like
select ID, name, description, ...
from myTable
where (colname like #flag + 'Flag') = 1
so if I call the sproc like exec uspMyProc #flag = 'foo' I'd get back rows 1 and 4.
I know I can't do the part in parens directly in SQL. In order to do dynamic SQL, I'll have to stuff the entire query into a string, concatenate the #flag param in the WHERE clause and then exec the string. Aside from the dirty feeling I get when doing dynamic SQL, my query is fairly large (I'm selecting a couple dozen fields, joining 5 tables, calling a couple of functions), so it's a big giant string all because of a single line in a 3-line WHERE filter.
Alternately, I could have 4 copies of the query and select among them in a CASE statement. This leaves the SQL code directly executable (and subject to syntax hilighting, etc.) but at the cost of repeating big chunks of code, since I can't use the CASE on just the WHERE clause.
Are there any other options? Any tricky joins or logical operations that can be applied? Or should I just get over it and exec the dynamic SQL?
There are a few ways to do this:
You can do this with a case statement.
select ID, name, description, ...
from myTable
where CASE
WHEN #flag = 'foo' then fooFlag
WHEN #flag = 'bar' then barFlag
END = 1
You can use IF.
IF (#flag = 'foo') BEGIN
select ID, name, description, ...
from myTable
where fooFlag = 1
END ELSE IF (#flag = 'bar') BEGIN
select ID, name, description, ...
from myTable
where barFlag = 1
END
....
You can have a complicated where clause with a lot of parentheses.
select ID, name, description, ...
from myTable
where (#flag = 'foo' and fooFlag = 1)
OR (#flag = 'bar' and barFlag = 1) OR ...
You can do this with dynamic sql:
DECLARE #SQL nvarchar(4000)
SELECT #SQL = N'select ID, name, description, ...
from myTable
where (colname like ''' + #flag + 'Flag'') = 1'
EXECUTE sp_ExecuteSQL #SQL, N''
There are more, but I think one of these will get you going.
"Alternately, I could have 4 copies of the query and select among them in a CASE statement."
You don't need to copy your entire query 4 times, just add all the possibilities into the where clauses in your single copy of the query:
select ID, name, description, ...
from myTable
where (#flag = 'foo' and fooFlag = 1) OR (#flag = 'bar' and barFlag = 1) OR ...
What I would do is CASE some variables at the beginning. Example:
DECLARE
#fooFlag int,
#barFlag int,
#bazFlag int,
#quuxFlag int
SET #fooFlag = CASE WHEN #flag = 'foo' THEN 1 ELSE NULL END
SET #barFlag = CASE WHEN #flag = 'bar' THEN 1 ELSE NULL END
SET #bazFlag = CASE WHEN #flag = 'baz' THEN 1 ELSE NULL END
SET #quuxFlag = CASE WHEN #flag = 'quux' THEN 1 ELSE NULL END
SELECT ID, name, description, ...
FROM myTable
WHERE (fooFlag >= ISNULL(#fooFlag, 0) AND fooFlag <= ISNULL(#fooFlag, 1))
AND (barFlag >= ISNULL(#barFlag, 0) AND barFlag <= ISNULL(#barFlag, 1))
AND (bazFlag >= ISNULL(#bazFlag, 0) AND bazFlag <= ISNULL(#bazFlag, 1))
AND (quuxFlag >= ISNULL(#quuxFlag, 0) AND quuxFlag <= ISNULL(#quuxFlag, 1))
The good thing about this query is that, because the possible values for "flags" are bounded, you can calculate all your conditionals as prerequisites instead of wrapping columns in them. This guarantees a high-performance index seek on whichever columns are indexed, and doesn't require writing any dynamic SQL. And it's better than writing 4 separate queries for obvious reasons.
You could have a parameter for each possible flag column, then check if the parameter is null or the value in the column is equal to the parameter. Then you pass in a 1 for the flags that you want to check and leave the others null.
select id, name, description, ...
from myTable
where (#fooFlag is null or fooFlag = #fooFlag) AND
(#barFlag is null or barFlag = #barFlag) AND
...
Honestly, though, this seems like an ideal candidate for building a dynamic LINQ query and skipping the SPROC once you get to SQL2008.
int should be accepted as varchar value
declare #CompanyID as varchar(10) = '' -- or anyother value
select * from EmployeeChatTbl chat
where chat.ConversationDetails like '%'+#searchKey+'%'
and
(
(0 = CASE WHEN (#CompanyID = '' ) THEN 0 ELSE 1 END)
or
(chat.CompanyID = #CompanyID)
)
working
when the companyID is present , then filtration based on it is done, other wise , filtration is skipped.
where
case when #value<>0 then Field else 1 end
=
case when #value<>0 then #value else 1 end
Related
I developed the following function:
create function kv_fn_ValuationPerItem_AW (#dDate date, #active bit)
returns table
as
return
(
select
Code ItemCode
, Description_1 ItemDescription
, ItemGroup
, Qty_On_Hand CurrentQtyOnHand
, AveUCst CurrentAvgCost
, Qty_On_Hand*AveUCst CurrentValue
from _bvSTTransactionsFull t
inner join StkItem s on t.AccountLink = s.StockLink
where ServiceItem = 0
and ItemActive = #active
and TxDate <= #dDate
group by Code, Description_1, ItemGroup, Qty_On_Hand, AveUCst
)
The function requires two parameters:
Date
Is the item Active - 1 = Active & 0 = Inactive
If I use the function as stipulated above, by specifying 1 for the Active Parameter, then the results will only be for Active Items.
If I specify 0, then it'll return all inactive Items.
How do I alter this function to cater for Active Items or both Active & Inactive?
i.e. if the parameter is 1, the where clause should read as ItemActive = #active, but when it's 0, the where clause should read as ItemActive in (1,0), How do I change the function to work like this?
I tried a case, but my syntax is not correct...
It's as simple as adding an or to your where cluase:
...
and (ItemActive = 1 OR #active = 0)
...
BTW, you might want to do it like this instead:
and (ItemActive = #active OR #active IS NULL)
which means that when you pass in 1 as #active you'll get only the active items, when you pass in 0 you'll get only the inactive members, but when you pass in null you'll get all records, regardless of the value in the ItemActive column.
Thanks Shnugo & Zohar for your answers,
Please amend your answers, then I'll mark yours as the answer.
The solution to my problem was to alter the Function as following:
create function kv_fn_ValuationPerItem_AW (#dDate date, #active bit)
returns table
as
return
(
select
Code ItemCode
, Description_1 ItemDescription
, ItemGroup
, Qty_On_Hand CurrentQtyOnHand
, AveUCst CurrentAvgCost
, Qty_On_Hand*AveUCst CurrentValue
from _bvSTTransactionsFull t
inner join StkItem s on t.AccountLink = s.StockLink
where ServiceItem = 0
and ItemActive in (1,#active)
and TxDate <= #dDate
group by Code, Description_1, ItemGroup, Qty_On_Hand, AveUCst
)
I think you are looking for this:
DECLARE #mockup TABLE(ID INT IDENTITY,SomeValue VARCHAR(100),Active BIT);
INSERT INTO #mockup VALUES('Row 1 is active',1)
,('Row 2 is active',1)
,('Row 3 is inactive',0)
,('Row 4 is inactive',0);
DECLARE #OnlyActive BIT=0; --set this to 1 to see active rows only
SELECT *
FROM #mockup m
WHERE (#OnlyActive=0 OR m.Active=1);
The idea is: If the parameter is set to 0 this expression is always true, if not, the column Active must be set to 1.
Hint: I used paranthesis, which was not needed in this simple case. But in your more complex WHERE clause they will be needed...
Hint2: I named the parameter OnlyActive, which expresses a bit better what you are looking for. You might turn the parameter to ShowAll with an invers logic too...
I have a table. I have 2 variables, one is a bit, the other is an int.
Table: WorkGroupCollectionDetail
Variables: #WorkgroupID int, #IsFSBP bit
The table has WorkGroupId int PK and WorkGroupCollectionCode varchar PK. That's it.
I can run a query like this:
SELECT WorkGroupId
FROM WorkGroupCollectionDetail
WHERE WorkGroupCollectionCode = 'FSBP'
and it gives me a list of WorkGroupID.
So what I need to do is if the value of #WorkgroupID is inside the results of that query, I need to set the bit variable to true.
select #IsFBSP = case
when exists (
select 42 from WorkGroupDetailCollection
where WorkGroupCollectionCode = 'FSBP' and WorkGroupId = #WorkGroupId ) then 1
else 0 end
which is logically equivalent to:
select #IsFBSP = case
when #WorkGroupId in (
select WorkGroupId from WorkGroupDetailCollection
where WorkGroupCollectionCode = 'FSBP' ) then 1
else 0 end
A query using EXISTS often performs better than a query using IN. You can check the execution plans to see how they compare in your particular case.
Note that these examples include setting the bit value to zero as well as one.
You could modify the SELECT to include the check for the WorkGroupId and update the #IsFSBP accordingly:
IF EXISTS(SELECT WorkGroupId
FROM WorkGroupCollectionDetail
WHERE WorkGroupCollectionCode = 'FSBP'
AND WorkGroupId = #WorkgroupID)
BEGIN
SELECT #IsFSBP = 1;
END
SQL Fiddle example
I'm guessing you're looking for
Set #BitVariable = count(*)
From TestTable
WHERE TestCode = 'TestValue' and TestID = #TestID
I am having problems returning a VARCHAR out of a derived column.
Below are extremely simplified code examples.
I have been able to do this before:
SELECT *, message =
CASE
WHEN (status = 0)
THEN 'aaa'
END
FROM products
But when I introduce a Common Table Expression or Derived Table:
WITH CTE_products AS (SELECT * from products)
SELECT *, message =
CASE WHEN (status = 0)
THEN 'aaa'
END
FROM CTE_products
this seems to fail with the following message:
Conversion failed when converting the varchar value 'aaa' to data type int.
When I tweak the line to say:
WITH CTE_products AS (SELECT * from products)
SELECT *, message =
CASE WHEN (status = 0)
THEN '123'
END
FROM CTE_products
It returns correctly.
...
When I remove all the other clauses prior to it, it also works fine returning 'aaa'.
My preference would be to keep this as a single, stand-alone query.
The problem is that the column is an integer dataype and sql server is trying to convert 'aaa' to integer
one way
WITH CTE_products AS (SELECT * from products)
SELECT *, message =
CASE WHEN (status = 0)
THEN 'aaa' else convert(varchar(50),status)
END
FROM CTE_products
I actually ended up finding the answer.
One of my CASE/WHEN clauses used a derived column from the CTE and that ended up causing the confusion.
Before:
WITH CTE_products AS (SELECT *, qty_a + qty_b as qty_total FROM products)
SELECT *, message =
CASE WHEN (status = 0)
THEN 'Status is 0, the total is: ' + qty_total + '!'
END
FROM CTE_products
Corrected:
WITH CTE_products AS (SELECT *, qty_a + qty_b as qty_total FROM products)
SELECT *, message =
CASE WHEN (status = 0)
THEN 'Status is 0, the total is: ' + CAST(qty_total AS VARCHAR) + '!'
END
FROM CTE_products
I ended up removing WHEN/THEN clauses within the CASE statement right afterwards to see if it was a flukey parentheses error when I realized that in the absence of any of the WHEN/THEN clauses that included the derived column from the CTE, it was able to return VARCHAR.
Can anyone tell me how to translate the following T-SQL statement:
SELECT fileld1 = CASE
WHEN T.option1 THEN -1
ELSE
CASE WHEN T.option2 THEN 0
ELSE 1
END
END
FROM Table1 AS T
The point is I need to validate two different options from the table for a single field in the select statement..
I have tried to do somthing with an IF statement in pl/sql, but it just doesnt work for me:
SELECT IF T.option1 THEN -1
ELSE IF T.option2 THEN 0
ELSE 1
END
FROM Table1 AS T
I am not actually sure how to write IF statement inside the SELECT statement..
And also, I need to do it INSIDE the select statement because I am constructing a view.
Use:
SELECT CASE
WHEN T.option1 = ? THEN -1
WHEN T.option2 = ? THEN 0
ELSE 1
END AS field1
FROM Table1 AS T
I can't get your original TSQL to work - I get:
Msg 4145, Level 15, State 1, Line 4
An expression of non-boolean type specified in a context where a condition is expected, near 'THEN'.
...because there's no value evaluation. If you're checking if the columns are null, you'll need to use:
SELECT CASE
WHEN T.option1 IS NULL THEN -1
WHEN T.option2 IS NULL THEN 0
ELSE 1
END AS field1
FROM Table1 AS T
...or if you need when they are not null:
SELECT CASE
WHEN T.option1 IS NOT NULL THEN -1
WHEN T.option2 IS NOT NULL THEN 0
ELSE 1
END AS field1
FROM Table1 AS T
CASE expressions shortcircuit - if the first WHEN matches, it returns the value & exits handling for that row - so the options afterwards aren't considered.
If I remember correctly, PL/SQL also supports the case. You just would have to move the column alias from "field1=" before the expression to "AS filed1" after the expression.
I have a huge query which uses case/when often. Now I have this SQL here, which does not work.
(select case when xyz.something = 1
then
'SOMETEXT'
else
(select case when xyz.somethingelse = 1)
then
'SOMEOTHERTEXT'
end)
(select case when xyz.somethingelseagain = 2)
then
'SOMEOTHERTEXTGOESHERE'
end)
end) [ColumnName],
Whats causing trouble is xyz.somethingelseagain = 2, it says it could not bind that expression. xyz is some alias for a table which is joined further down in the query. Whats wrong here? Removing one of the 2 case/whens corrects that, but I need both of them, probably even more cases.
SELECT
CASE
WHEN xyz.something = 1 THEN 'SOMETEXT'
WHEN xyz.somethingelse = 1 THEN 'SOMEOTHERTEXT'
WHEN xyz.somethingelseagain = 2 THEN 'SOMEOTHERTEXTGOESHERE'
ELSE 'SOMETHING UNKNOWN'
END AS ColumnName;
As soon as a WHEN statement is true the break is implicit.
You will have to concider which WHEN Expression is the most likely to happen. If you put that WHEN at the end of a long list of WHEN statements, your sql is likely to be slower. So put it up front as the first.
More information here: break in case statement in T-SQL
declare #n int = 7,
#m int = 3;
select
case
when #n = 1 then
'SOMETEXT'
else
case
when #m = 1 then
'SOMEOTHERTEXT'
when #m = 2 then
'SOMEOTHERTEXTGOESHERE'
end
end as col1
-- n=1 => returns SOMETEXT regardless of #m
-- n=2 and m=1 => returns SOMEOTHERTEXT
-- n=2 and m=2 => returns SOMEOTHERTEXTGOESHERE
-- n=2 and m>2 => returns null (no else defined for inner case)
If logical test is against a single column then you could use something like
USE AdventureWorks2012;
GO
SELECT ProductNumber, Category =
CASE ProductLine
WHEN 'R' THEN 'Road'
WHEN 'M' THEN 'Mountain'
WHEN 'T' THEN 'Touring'
WHEN 'S' THEN 'Other sale items'
ELSE 'Not for sale'
END,
Name
FROM Production.Product
ORDER BY ProductNumber;
GO
More information - https://learn.microsoft.com/en-us/sql/t-sql/language-elements/case-transact-sql?view=sql-server-2017