Does this query require dynamic sql? SQL Server - sql

Question

I want to select the parameters of a stored procedure and then check whether each parameter is null or not in a loop.
The problem I'm having is that when I want to evaluate the variable in the IF statement, it is not being evaluated correctly. I want to evaluate each parameter I stored in the table variable. I don't know the syntax for this...or maybe it isn't even possible?
Does this require Dynamic SQL? If so, when executing dynamic sql, the value of the variable will be out of scope so how do I deal with that?
I verified everything up to the IF statement works.
CREATE PROCEDURE dbo.UpdateBank
(
#BankKey [smallint] = NULL,
#Bank [varchar] (30) = NULL,
#BankCode [char] (4) = NULL,
#MasterBankCode [char] = NULL,
#Bin [char] (6) = NULL,
#WebSite [varchar] (50) = NULL,
#isActive [bit] = NULL,
#CreateDate [smalldatetime] = NULL
)
AS
SET NOCOUNT ON
SET ANSI_NULLS OFF
DECLARE #MaxRow TINYINT, #Count TINYINT
DECLARE #SPName VARCHAR (128), #CurrentRow TINYINT
SET #SPName = OBJECT_NAME(##PROCID) -- SP self-reference to find its current name
DECLARE #SPParametersList TABLE (ID INT Identity(1,1) Primary Key,
ParameterName NVARCHAR (128),
DataType NVARCHAR (128),
ParameterMode NVARCHAR (10))
CREATE TABLE #TempExec(ID INT Identity(1,1) Primary Key,
Num BIT)
INSERT INTO #SPParametersList (ParameterName, Datatype, ParameterMode)
SELECT PARAMETER_NAME,DATA_TYPE,PARAMETER_MODE
FROM INFORMATION_SCHEMA.PARAMETERS
WHERE SPECIFIC_NAME = #SPName
SET #CurrentRow = 1
SELECT #MaxRow = ISNULL(MAX(ID),0) FROM #SPParametersList
WHILE #CurrentRow <= #MaxRow
BEGIN
IF ((SELECT ParameterName FROM #SPParametersList WHERE ID = #CurrentRow) <> NULL)
BEGIN
SELECT 'Success'
SET #Count = #Count + 1
END
SELECT 'Fail'
SET #CurrentRow = #CurrentRow + 1
END
SELECT #Count
I always get 'Fail' when I run this stored proc

Answer 1

Change your line:
IF ((SELECT ParameterName FROM #SPParametersList WHERE ID = #CurrentRow) <> NULL)
to
IF ((SELECT ParameterName FROM #SPParametersList WHERE ID = #CurrentRow) IS NOT NULL)
You also need to initialize the #Count variable to 0:
SET #Count = 0
SET #CurrentRow = 1
SELECT #MaxRow = ISNULL(MAX(ID),0) FROM #SPParametersList

Answer 2

Probably the issue is in the <> NULL which should
IF EXISTS(SELECT ParameterName FROM #SPParametersList WHERE ID = #CurrentRow)
but I'm not sure what you want to achieve with that piece of code...

Answer 3

I suspect that this is an example of a query that can be rewritten without the use of loops/cursors (most sql is in my experience...)
Does the query below give you your desired results?
with temp as
(
SELECT '#BankKey' as ParamName
UNION
SELECT '#Bank'
)
SELECT COUNT(*) as myCount
FROM INFORMATION_SCHEMA.PARAMETERS as isp
LEFT JOIN temp as t
ON t.ParamName = isp.PARAMETER_NAME
WHERE SPECIFIC_NAME = #SPName AND t.ParamName is null
You should try to avoid using Loops/Cursors as much as possible. SQL Server (and most DBMSs in general) are excellent at performing Set based operations and terrible at performing row based operations (loops/cursors).

Answer 4

(1) "I always get 'Fail' when I run this stored proc": you have forget the ELSE branch
IF ((SELECT ParameterName FROM #SPParametersList WHERE ID = #CurrentRow) /*<>*/ IS NOT NULL)
BEGIN
SELECT 'Success'
SET #Count = #Count + 1
END
ELSE -- << here
BEGIN
SELECT 'Fail'
END
SET #CurrentRow = #CurrentRow + 1
(2) To count all not null parameters:
SELECT #Count=COUNT(*)
FROM #SPParametersList a
WHERE a.ParameterName IS NOT NULL
To count all null parameters:
SELECT #Count=COUNT(*)
FROM #SPParametersList a
WHERE a.ParameterName IS NULL
Note: if you want to test for NULL / NOT NULL you should use column/#variable IS [NOT] NULL operator and SET ANSI_NULLS must be ON: SET ANSI_NULLS ON.