SQL LEFT JOIN Query reporting with optional parameters - sql

Question

I'm running a query that generates a report for an inventory system. The query takes in 6 parameters, 3 of which are optional. The query works fine if all the parameters are entered, however I can't get the query to operate correctly when one or more optional parameters are omitted.
The important parameters are #AccountNumber, #Branch, #Department, and #OrderBy. The #AccountNumber parameter is required while the other three are optional. If #Branch is omitted I would like the report to show all of the inventory in that account. Similarly, If #Department is omitted but #Branch is present I would like to show all of the inventory in that account's branch. If all three parameters are present then it will show all of the inventory in that account's branch and department. If #OrderBy is omitted then the report orders the inventory by account number ordered ascending by default. The query that I'm using is below:
USE database;
GO
CREATE PROCEDURE RetrievedList
#AccountNumber int,
#Branch nvarchar(50),
#Department nvarchar(50),
#StartDate date,
#EndDate date,
#OrderBy nvarchar(10)
AS
IF #OrderBy = 'Locator'
BEGIN
SELECT [Container].[Acct] AS [Account]
...
FROM [File] LEFT JOIN [Container]
ON [File].[BoxID] = [Container].[BoxID]
WHERE [Container].[Acct] = #AccountNumber
AND [Container].[Branch] = #Branch
AND [Container].[Dept] = #Department
AND [File].[Out_Date] IS NOT NULL
AND [File].[Out_Date] BETWEEN #StartDate AND #EndDate
ORDER BY [Container].[Loc];
END
ELSE IF #OrderBy = 'Title'
BEGIN
SELECT [Container].[Acct] AS [Account]
...
FROM [File] LEFT JOIN [Container]
ON [File].[BoxID] = [Container].[BoxID]
WHERE [Container].[Acct] = #AccountNumber
AND [Container].[Branch] = #Branch
AND [Container].[Dept] = #Department
AND [File].[Out_Date] IS NOT NULL
AND [File].[Out_Date] BETWEEN #StartDate AND #EndDate
ORDER BY [File].[Title1];
END
ELSE
BEGIN
SELECT [Container].[Acct] AS [Account]
...
FROM [File] LEFT JOIN [Container]
ON [File].[BoxID] = [Container].[BoxID]
WHERE [Container].[Acct] = #AccountNumber
AND [Container].[Branch] = #Branch
AND [Container].[Dept] = #Department
AND [File].[Out_Date] IS NOT NULL
AND [File].[Out_Date] BETWEEN #StartDate AND #EndDate
ORDER BY [Container].[Acct], [Container].[Branch], [Container].[Dept], [Container].[BoxNo], [File].[Title1];
END
GO
Keep in mind that I can't use the WHERE [Container].[Branch] = #Branch OR [Container].[Branch] = NULL approach because of the LEFT JOIN; it returns six times the records that are expected.

Answer 1

My typical pattern for this issue is using the IsNull operator like this:
AND [Container].[Branch] = IsNull(#Branch, [Container].[Branch])
It will compare against the parameter if passed; otherwise, it'll compare the column to itself.

Answer 2

#bassrek is right you can compare against itself for that matter you can create a case expression in the JOIN conditions and make things whatever value you really want. One more thing to note though if the only thing that is changing in your query is the order by why not write a series of case statments in your order by to do the ordering you desire instead of copying the same query 3 times and then changing the order by. It will make it easier to maintain your business logic should changes need to be made.
another method instead of having to compare against itself instead for performance as Sean suggests could be to use the IN operator and deal with the null:
ISNULL(#Branch,'') IN ([Container].[Branch],'')
for Example you could do the following to make #Branch, #Department, and #OrderBy optional and combine all 3 selects into a single statement:
SELECT [Container].[Acct] AS [Account]
...
FROM [File] LEFT JOIN [Container]
ON [File].[BoxID] = [Container].[BoxID]
WHERE [Container].[Acct] = #AccountNumber
AND ISNULL(#Branch,'') IN ([Container].[Branch],'')
AND ISNULL(#Department,'') IN ([Container].[Dept],'')
AND [File].[Out_Date] IS NOT NULL
AND [File].[Out_Date] BETWEEN #StartDate AND #EndDate
ORDER BY
CASE
WHEN ISNULL(#OrderBy,'') = 'Locator' THEN [Container].[Loc]
WHEN ISNULL(#OrderBy,'') = 'Title' THEN [File].[Title1]
ELSE [Container].[Acct]
END
,CASE
WHEN LEN(ISNULL(#OrderBy,'')) <> 0 THEN '1'
ELSE [Container].[Branch]
END
,CASE
WHEN LEN(ISNULL(#OrderBy,'')) <> 0 THEN '1'
ELSE [Container].[Dept]
END
,CASE
WHEN LEN(ISNULL(#OrderBy,'')) <> 0 THEN '1'
ELSE [Container].[BoxNo]
END
,CASE
WHEN LEN(ISNULL(#OrderBy,'')) <> 0 THEN '1'
ELSE [File].[Title1]
END