I am designing a SQL query to extract all records from a given table. But the trick here is that this logic is based on a numeric database field. So there are 4 choices: 0,1,2,3. If user selects 0,1, or 2, then my query returns rows with the specified value. But if they choose 3, it should return all of the rows. How do I do this in SQL? I know if this was a string, I could do something like:
WHERE = CASE WHEN = 3 THEN '%' ELSE END
But in this case, is an integer. Sounds relatively simple but I'm getting errors.
Try this:
SELECT *
FROM <YOUR_TABLE>
WHERE
(
<YOUR_COLUMN> = #InputValue OR
3 = #InputValue
)
Where #InputValue is the name of parameter sent to the query.
The simplest way is to do this:
select MyColumn
from MyTable
where ( MyValue = #MyParameter or #MyParameter = 3)
If your interested in better optimization, then you can do this, but it is less maintainable:
if (#MyParameter = 3)
select MyColumn
from MyTable
else
select MyColumn
from MyTable
where MyValue = #MyParameter
If I were forced to implement this functionality, then I would probably do this, just to make things clear:
declare #AllRecords nchar(1)
if (#MyParameter = 3)
set #AllRecords = N'Y'
else
set #AllRecords = N'N'
select MyColumn
from MyTable
where (MyValue = #MyParameter or #AllRecords = N'Y')
Hopefully, I won't ever have to implement a system that mixes flags and data value in this way.
UPDATED
Here is a version that should work with your expanded requirements (this requires one of the newer versions of SQL Server, I think):
declare #SelectedLevels table (LevelId int not null primary key)
if #LevelId = 3
insert into #SelectedLevels (LevelId) values (1), (2)
else if #LevelId = 5
insert into #SelectedLevels (LevelId) values (0), (1), (2)
else
insert into #SelectedLevels (LevelId) values (#LevelId)
select mt.MyColumn
from MyTable mt
inner join #SelectedLevels sl on sl.LevelId = MyTable.LevelId
if #Param = 3
begin
select *
from #T
end
else
if #Param = 2
begin
select *
from #T
where id in (0,1)
end
else
begin
select *
from #T
where id = #Param
end
Related
Apologies if my question seems to be naive:
I cannot get my head around the 2 statements below, can someone please explain the difference:
OUTPUT $ACTION, INSERTED.BuildRequestID, ..... and
PRINT ##ROWCOUNT
Apparently, they both can be used to print something on the window, with output in the example above, the records that have been inserted will be displayed. And, PRINT ##ROWCOUNT returns the number of rows affected by the last executed statement in the batch, so, if the function was insert, then it will show the inserted records?
Thank you,
In its simplest terms, OUTPUT will give you the actual records affected by a DML statement (INSERT, UPDATE, DELETE, MERGE), ##ROWCOUNT will just tell you how many rows were affected by the previous Statement (not limited to DML).
This is probably easiest understood with a working example that you can run yourself and see both in action:
IF OBJECT_ID(N'tempdb..#T', 'U') IS NOT NULL
DROP TABLE #T;
-- CHECK ##ROWCOUNT
DECLARE #RowCountFromDropTable INT = ##ROWCOUNT;
-- CREATE A TABLE
CREATE TABLE #T (ID INT NOT NULL PRIMARY KEY, Col CHAR(1) NOT NULL);
-- INSERT SOME VALUES AND CHECK THE OUTPUT
INSERT #T (ID, Col)
OUTPUT inserted.*
VALUES (1, 'A'), (2, 'B'), (3, 'C');
-- CHECK ##ROWCOUNT
DECLARE #RowCountFromInsert INT = ##ROWCOUNT;
-- DELETE A VALUE AND INSPECT THE DELETED RECORD WITH OUTPUT
DELETE #T
OUTPUT deleted.*
WHERE ID = 3;
-- CHECK ##ROWCOUNT
DECLARE #RowCountFromDelete INT = ##ROWCOUNT;
-- UPDATE A RECORD AND VIEW BEFORE AND AFTER VALUES
UPDATE #T
SET Col = 'X'
OUTPUT inserted.ID AS ID,
inserted.Col AS UpdatedTo,
deleted.Col AS UpdatedFrom
WHERE ID = 2;
-- CHECK ##ROWCOUNT
DECLARE #RowCountFromUpdate INT = ##ROWCOUNT;
-- USE MERGE, AND CAPTURE ACTION:
MERGE #T AS t
USING (VALUES (2, 'B'), (3, 'C')) AS s (ID, Col)
ON s.ID = t.ID
WHEN NOT MATCHED THEN INSERT (ID, Col) VALUES (s.ID, s.Col)
WHEN MATCHED THEN UPDATE SET Col = s.Col
WHEN NOT MATCHED BY SOURCE THEN DELETE
OUTPUT $Action AS DMLAction,
inserted.ID AS InsertedID,
inserted.Col AS InsertedCol,
deleted.ID AS DeletedID,
deleted.Col AS DeletedCol;
-- CHECK ##ROWCOUNT
DECLARE #RowCountFromMerge INT = ##ROWCOUNT;
SELECT RowCountFromDropTable = #RowCountFromDropTable,
RowCountFromInsert = #RowCountFromInsert,
RowCountFromDelete = #RowCountFromDelete,
RowCountFromUpdate = #RowCountFromUpdate,
RowCountFromMerge = #RowCountFromMerge;
The recordsets output from each of the DML are:
INSERT
ID Col
-------
1 A
2 B
3 C
DELETE
ID Col
-------
3 C
UPDATE
ID UpdatedTo UpdatedFrom
---------------------------
2 X B
MERGE
DMLAction InsertedID InsertedCol DeletedID DeletedCol
------------------------------------------------------------
INSERT 3 C NULL NULL
DELETE NULL NULL 1 A
UPDATE 2 B 2 X
INSPECT ##ROWCOUNTS
RowCountFromDropTable RowCountFromInsert RowCountFromUpdate RowCountFromMerge
--------------------------------------------------------------------------------
0 3 1 3
A quick point on some wording in the qeustion too: You cannot use OUTPUT directly to print something to the window, it returns records much like a SELECT statement. ##ROWCOUNT can be used like any scalar function, so you could use this in consecutive statements. So you could do something like this:
SELECT TOP (1) *
FROM (VALUES (1), (2), (3)) AS t (ID);
SELECT TOP (##ROWCOUNT + 1) *
FROM (VALUES (1), (2), (3)) AS t (ID);
SELECT TOP (##ROWCOUNT + 1) *
FROM (VALUES (1), (2), (3)) AS t (ID);
Which returns 1, 1,2 and 1,2,3 respectively. I have no idea why you would want to do this, but it demonstrates the scope of ##ROWCOUNT a bit better than the above, and how it can be used elsewhere.
I need to return a value if select returned null. however I found a solution here by putting a query in a sub-query
SELECT COALESCE((SELECT id FROM tbl WHERE id = 9823474), 4) AS id FROM RDB$DATABASE;
The query above would return Null because the value 9823474 does not exist in the table but I want to return a value in that case (for ex 4) so I found the only solution to use select inside sub query and then COALESCE would work, If I did not do that COALESCE will also return Null.
Is it the only solution ?
No, that is not an only way for example
Select first 1 id from (
Select id FROM tbl WHERE id = 9823474
Union All
Select 4 from rdb$database)
Or you can use anonymous procedure http://firebirdsql.su/doku.php?id=execute_block
EXECUTE BLOCK RETURNS ( id integer )
AS
BEGIN
IF ( EXISTS (SELECT * FROM tbl WHERE id = 9823474) )
THEN id = 9823474;
ELSE id = 4;
SUSPEND;
END
... there always are many methods there
We have a loop in SQL Server 2005 that loops around on a table getting each items parent until it gets to the top of the tree:
DECLARE #T Table
(
ItemID INT NOT NULL PRIMARY KEY,
AncestorID INT NULL
)
Which has data like this:
ItemID | AncestorID
1 2
2 3
3 4
4 NULL
We have a loop that basically does this:
DECLARE #AncestorID INT
SELECT #AncestorID = 1
WHILE (#AncestorID IS NOT NULL)
BEGIN
--Do some work
SELECT #AncestorID = T.AncestorID
FROM #T t
WHERE T.ItemID = #AncestorID
print #AncestorID
END
(Yes I know SQL is set based, and this is processing row by row, the "Do some work" needs to be done line by line for a reason).
This has always worked fine until today when we ended up in an endless loop. Turns out the cause was some wrong data:
ItemID | AncestorID
1 2
2 3
4 NULL
ItemID 3 was deleted. The loop now never ends because AncestorID is never NULL - it stays at 3.
Is there anyway to rewrite the select statement to make #AncestorID null if the SELECT query returns 0 rows, or do I need to have a separate SELECT statement to count the records and some IF ELSE type logic?
Is there anyway to rewrite the select statement to make #AncestorID
null if the SELECT query returns 0 rows,
You can use an aggregate on T.AncestorID.
SELECT #AncestorID = min(T.AncestorID)
FROM #T t
WHERE T.ItemID = #AncestorID
You could use another variable, e.g. #PreviousAncestorId, to hold the previous value and reset #AncestorId to NULL before the query.
You could check ##RowCount after the query to see if a row was found.
The code will still have issues dealing with cycles of arbitrary length within the data, e.g. a row where both values are the same. You would need to keep track of the visited rows in order to detect cycles. A simple reality check would be to count the number of iterations of the loop and check it against the number of rows.
Use a Break
e.g.
WHILE (#AncestorID IS NOT NULL)
BEGIN
SELECT T.AncestorID INTO #TEMP
FROM #T t WHERE T.ItemID = #AncestorID
IF((SELECT COUNT(*) FROM #TEMP) = 0) BREAK;
SELECT #AncestorID=T.AncestorID
FROM #TEMP t
print #AncestorID
DROP TABLE #TEMP
END
I'm trying to build a stored procedure that makes use of another stored procedure. Taking its result and using it as part of its where clause, from some reason I receive an error:
Invalid object name 'dbo.GetSuitableCategories'.
Here is a copy of the code:
select distinct top 6 * from
(
SELECT TOP 100 *
FROM [dbo].[products] products
where products.categoryId in
(select top 10 categories.categoryid from
[dbo].[GetSuitableCategories]
(
-- #Age
-- ,#Sex
-- ,#Event
1,
1,
1
) categories
ORDER BY NEWID()
)
--and products.Price <=#priceRange
ORDER BY NEWID()
)as d
union
select * from
(
select TOP 1 * FROM [dbo].[products] competingproducts
where competingproducts.categoryId =-2
--and competingproducts.Price <=#priceRange
ORDER BY NEWID()
) as d
and here is [dbo].[GetSuitableCategories] :
if (#gender =0)
begin
select * from categoryTable categories
where categories.gender =3
end
else
begin
select * from categoryTable categories
where categories.gender = #gender
or categories.gender =3
end
I would use an inline table valued user defined function. Or simply code it inline is no re-use is required
CREATE dbo.GetSuitableCategories
(
--parameters
)
RETURNS TABLE
AS
RETURN (
select * from categoryTable categories
where categories.gender IN (3, #gender)
)
Some points though:
I assume categoryTable has no gender = 0
Do you have 3 genders in your categoryTable? :-)
Why do pass in 3 parameters but only use 1? See below please
Does #sex map to #gender?
If you have extra processing on the 3 parameters, then you'll need a multi statement table valued functions but beware these can be slow
You can't use the results of a stored procedure directly in a select statement
You'll either have to output the results into a temp table, or make the sproc into a table valued function to do what you doing.
I think this is valid, but I'm doing this from memory
create table #tmp (blah, blah)
Insert into #tmp
exec dbo.sprocName
A UI (before the report shows) shows a look up (Combo) that has
(ID = 0).All Organization Units
(ID =4).HR
(ID = 5).DEV
I need to:
Be able to show data of (4) + (5) if
(0) is selected.
Only (4) OR (5) if either HR or DEV is selected.
Lookup combo code (Selected Feeds the parameter in the below query.)
Select 0 AS ID,'All Org' AS Name from DP_ORG_OrganizationUnit
where DP_ORG_OrganizationUnit.Code IN {AccessData}
Union
SELECT
DP_ORG_OrganizationUnit.ID,
DP_ORG_OrganizationUnit.Name
FROM DP_ORG_OrganizationUnit where DP_ORG_OrganizationUnit.Code IN ('HR','DEV')
Report data row query
SET CONCAT_NULL_YIELDS_NULL OFF
DECLARE #EmpID as int;
DECLARE #OrganizationUnit as int;
DECLARE #StartDate as datetime;
DECLARE #EndDate as datetime;
SET #EmpID = ?;
SET #StartDate = ?;
SET #EndDate = ?;
SET #OrganizationUnit = ?;
SELECT
Employee.Code,
Employee.Name1+' '+Employee.Name2+' '+Employee.Name3+' '+Employee.Name4+' '+Employee.Name5 AS FullName,
Employee.OrganizationUnit,
ContractType.Name,
EmployeeContract.StartDate,
EmployeeContract.EndDate
FROM Employee INNER JOIN (ContractType INNER JOIN EmployeeContract
ON ContractType.ID = EmployeeContract.ContractType)
ON Employee.ID = EmployeeContract.Employee
WHERE (Employee.ID = #EmpID OR #EmpID=0)
AND
(Employee.OrganizationUnit = #OrganizationUnit OR #OrganizationUnit=0)
AND NOT((EndDate < #StartDate or StartDate > #EndDate));
Any way I can achieve it from the looks of it? 0=0 would show all the data from other
departments too..
Anybody :-o?
First off, your lookup combo code could be tightened up a bit:
-- the FROM clause was superfluous
SELECT 0 AS ID,'All Org' AS Name
UNION ALL
-- the two-part identifiers were superfluous (only one table)
SELECT ID, Name
FROM DP_ORG_OrganizationUnit
WHERE Code IN ('HR','DEV')
For the report query, the simplest form would be:
WHERE
((#OrganizationUnit > 0 AND Employee.OrganizationUnit = #OrganizationUnit) OR
(#OrganizationUnit = 0 AND Employee.OrganizationUnit IN (4,5)))
something like this should work
Where (Employee.OrganizationUnit = case when #OrganizationUnit=0 then 4 else #OrganizationUnit end OR case when #OrganizationUnit=0 then 5 else #OrganizationUnit end)
Try this, which should use indexes on your query...
DECALRE #FilterValues (FilterValue int not null primary key)
IF #Param=0
BEGIN
INSERT INTO #FilterValues VALUES (4)
INSERT INTO #FilterValues VALUES (5)
END
ELSE ID #PAram IS NOT NULL
BEGIN
INSERT INTO #FilterValues VALUES (#Param)
END
SELECT
....
FROM YourTable y
INNER JOIN #FilterValues f ON y.Value=f.Value
WHERE .....
KM's version will work, but this query does not need a temp table...
SELECT *
FROM Employee
WHERE (
#OrganizationUnit = 0
OR
(
#OrganizationUnit <> 0
AND
Employee.OrganizationUnit = #OrganizationUnit
)
)
How about
WHERE (Employee.ID = #EmpID OR #EmpID=0)
AND
(Employee.OrganizationUnit BETWEEN ISNULL(NULLIF(#OrganizationUnit,0),0) AND ISNULL(NULLIF(#OrganizationUnit,0),99))
AND NOT((EndDate < #StartDate or StartDate > #EndDate));