Dynamic SQL Query (variable entries, and variable entries per column)

Question

Sorry for the long post, but most of it is code spelling out my scenario:

I'm trying to execute a dynamic query (hopefully through a stored proceedure) to retrieve results based on a variable number of inputs.

If I had a table:

(dbo).(People)
ID   Name   Age
1    Joe    28
2    Bob    32
3    Alan   26
4    Joe    27

I want to allow the user to search by any of the three columns, no problem:

DECLARE @ID int, @Name nvarchar(25), @Age int
SET @ID = 1
SET @Name = 'Joe'
SET @Age = null

SELECT *
FROM dbo.People
WHERE
(ID = @ID or @ID is null) AND
(Name like @Name or @Name is null) AND
(Age = @Age or @Age is null)

And I retrieve the result that I want.

Now, if I want to search for multiple fields in a column, I can do that no problem:

DECLARE @text nvarchar(100)
SET @text = '1, 3'

DECLARE @ids AS TABLE (n int NOT NULL PRIMARY KEY)

--//parse the string into a table
DECLARE @TempString nvarchar(300), @Pos int
SET @text = LTRIM(RTRIM(@text))+ ','
SET @Pos = CHARINDEX(',', @text, 1)
IF REPLACE(@text, ',', '') <> ''
BEGIN
    WHILE @Pos > 0
    BEGIN
        SET @TempString = LTRIM(RTRIM(LEFT(@text, @Pos - 1)))
        IF @TempString <> '' --just: IF @TempString != ''
        BEGIN
            INSERT INTO @ids VALUES (@TempString)
        END
        SET @text = RIGHT(@text, LEN(@text) - @Pos)
        SET @Pos = CHARINDEX(',', @text, 1)
    END
END


SELECT *
FROM   dbo.People
WHERE  
ID IN (SELECT n FROM @ids)

Now, my issue is I can't seem to figure out how to combine the two since I can't put:

WHERE
(Name like @Name or @Name is null) AND
(Id IN (SELECT n FROM @ids) or @ids is null)

Because @ids will never be null (since it's a table)

Any help would be greatly appreciated!

Thanks in advance...and let me know if I can clarify anything

Answer 1

You can try:

NOT EXISTS (SELECT 1 FROM @ids)
OR EXISTS (SELECT 1 FROM @ids where n = Id) 

But these better be small tables - this query will probably not play very well with any indexes on your tables.

Answer 2

You could use an IF statement:

IF LEN(@ids) > 0
BEGIN

  SELECT *
    FROM dbo.People
   WHERE ID IN (SELECT n FROM @ids)

END
ELSE
BEGIN

  SELECT *
    FROM dbo.People

END

Otherwise, consider making the query real dynamic SQL (minding pitfalls of course).

Answer 3

Try:

(Id IN (SELECT n FROM @ids) OR NOT EXISTS (SELECT * FROM @ids))

Answer 4

A quick fix:

(`%,' + Id + ',%' like ',' + @ids + ',' or @ids is null)
and (`%,' + Name + ',%' like ',' + @names + ',' or @names is null)

So if the user passes @ids = 1,2, the first row gives:

`%,1,%' like ',1,2,'

It's a good idea to filter out spaces before and after comma's. :)