使用Like运算符的Where子句中的CASE语句

Question

I am facing an issue using CASE expression in where clause, To my knowledge syntax is correct but getting a error. Below is my code:

Where
CASE 
            WHEN (@ItemFor='' and @ItemTo='')
            THEN id like '%'
            ELSE id between @ItemFor and @ItemTo
        END

Above code looks correct to me but I am getting syntax error saying

Incorrect syntax near the keyword 'like'.

Edit

I have 4 sets of parameters and all need to go to where clause and all are string values:

WHERE

        CASE 
            WHEN (@ItemFor='' and @ItemTo='')
                THEN id like '%'
                ELSE id between @ItemFor and @ItemTo
        END
    AND 
        CASE 
            WHEN (@CodeFrom='' and @CodeTo='')
            THEN Code like '%'
            ELSE code between @CodeFrom and @CodeTo
        END

Answer 1

You don't need a case expression for this. Just do:

where ((@ItemFor = '' and @ItemTo = '') or
       id between @ItemFor and @ItemTo
      )

Your version doesn't work because SQL Server doesn't have boolean variables. Your a case expression is trying to return a boolean expression, but such an expression is not a value.

By the way, you probably intend:

where (id >= @itemfrom or @itemfrom = '') and
      (id <= @itemto or @itemto = '')

This allows you to set only one of the limits.

Answer 2

You could simplify and use this condition:

WHERE ((@ItemFor='' and @ItemTo='' AND id like '%') OR id between @ItemFor and @ItemTo)
  AND ((@CodeFrom='' and @CodeTo='' AND Code like '%') OR code between @CodeFrom and @CodeTo)

and now syntax is correct.

Moreover, id like '%' and Code like '%' make no sense, because they are always true. They can be read as "check if id (or Code ) is anything", so they can (should) be removed.

Answer 3

This may solve your problem:

WHERE 
((@ItemFor = '' and @ItemTo = '' and id like '%') 
or (@ItemFor <> '' and @ItemTo <> '' and id between @ItemFor and @ItemTo))      
AND 
((@CodeFrom = '' and @CodeTo = '' and Code like '%')
 or (@CodeFrom <> '' and @CodeTo <> '' and code between @CodeFrom and @CodeTo))

Answer 4

Since CASE cannot return a boolean value, you'll have to return something else and compare:

WHERE
  CASE
    WHEN Condition1 THEN 1
    WHEN Condition2 THEN 0
    WHEN Condition3 THEN 1
    ELSE 0
  END = 1

Answer 5

Try this approach instead.

where (@itemFor='' and @itemto='') OR (id between @itemFor and @itemto)

Doing the same as your case case statement. If both variables are empty, then don't filter the ID clause. If the variables are populated, check the ID within range

Note that if you are doing multiple conditions, I would suggest adding extra parenthesis, such as

where ( (@itemFor='' and @itemto='') OR (id between @itemFor and @itemto) )
   and (firstName like '%JOE%')

etc

Answer 6

To explain what's wrong with the CASE WHEN.

A CASE WHEN returns a value, which you can choose depending on different criteria.
And it returns a value based on the first criteria that matches.
Hence, it's not supposed to return a criteria.

The example below makes use of that.

WHERE
   (CASE 
    WHEN @ItemFor='' AND @ItemTo='' AND id IS NOT NULL THEN 1
    WHEN id BETWEEN @ItemFor AND @ItemTo THEN 2
    ELSE 0
    END) > 0
   AND
   (CASE 
    WHEN @CodeFor='' AND @CodeTo='' AND Code IS NOT NULL THEN 1
    WHEN Code BETWEEN @CodeFor AND @CodeTo THEN 2
    ELSE 0
    END) > 0

That said, regarding this example.
A solution that doesn't use a CASE WHEN in the WHERE clause, is probably the better approach.

Example:

WHERE id IS NOT NULL
  AND Code IS NOT NULL
  AND ((@ItemFor='' AND @ItemTo='') OR (id BETWEEN @ItemFor AND @ItemTo))
  AND ((@CodeFor='' AND @CodeTo='') OR (Code BETWEEN @CodeFor AND @CodeTo))

Because it's harder for the query optimizer to choose the fastest execution plan based on a CASE WHEN.

Answer 7

Try this:

WHERE

CASE 
    WHEN (@ItemFor='' AND @ItemTo='') THEN 1
    WHEN (id between @ItemFor and @ItemTo) THEN 1
    WHEN (@CodeFrom='' and @CodeTo='') THEN 1
    WHEN (code between @CodeFrom and @CodeTo) THEN 1
    ELSE 0
END = 1

Answer 8

i guess your mistake area

WHERE

    CASE 
        WHEN (@ItemFor='' and @ItemTo='')
            THEN id like '%'                  -------conditional operator in result
            ELSE id between @ItemFor and @ItemTo ---------- conditional operator
    END
AND 
    CASE 
        WHEN (@CodeFrom='' and @CodeTo='')
        THEN Code like '%'
        ELSE code between @CodeFrom and @CodeTo  -------------conditional operator
    END

you can try below way

WHERE    
case when (@ItemFor='' and @ItemTo='') and id like '%' 
Then (case when id >=@ItemFor and id<=@ItemTo then id else end)
Else 
case when (@CodeFrom='' and @CodeTo='') and Code like '%' 
Then (case when code >=@ItemFor and code<=@ItemTo then code else end)
end