Append string in where clause in SQL - sql

Question

I have a function in SQL that returns where clause result like this
CREATE FUNCTION dwd.GetSearchCriteria
(
#pValue NVARCHAR(50),
#pCriteriaOption NVARCHAR(3)
)
RETURNS varchar(30)
AS
BEGIN
declare
#WHERE varchar(2000)
IF(#pValue IS NOT NULL)
BEGIN
SET #WHERE = CASE WHEN #pCriteriaOption = 'ST' THEN ' like ''' + #pValue + '%'''
WHEN #pCriteriaOption = 'ET' THEN ' like ''' + '%' + #pValue + ''''
WHEN #pCriteriaOption = 'CT' THEN ' like ' + '''%' + #pValue + '%'''
ELSE ''
END
END
ELSE
BEGIN
SET #WHERE = '= NULL';
END
RETURN #WHERE
END
I have a query that like this which calls this function
declare
#WHERE varchar(2000)
SET #WHERE=dwd.GetSearchCriteria ('A','ET')
SELECT FirstName FROM dwd.[User] WHERE FirstName + #WHERE
My function returns suppose { like %A% } . I need to append it to first name .
It returns this error
An expression of non-boolean type specified in a context where a
condition is expected, near '#WHERE'.
I have along SP like this
ALTER PROCEDURE [dwd].[ADMIN_USER_DETAIL]
(
#pApplicationClientID bigint,
#pUserID bigint,
/* Optional Filters for Dynamic Search*/
#pFirstName nvarchar(50) = NULL,
#pLastName nvarchar(50) = NULL,
#pEmail nvarchar(255) = NULL,
#pLocation nchar(10) = NULL,
#pPhoneNumber nvarchar(50) = NULL,
#pPseudoName nvarchar(500) = NULL,
/*– Pagination Parameters */
#pPageNo INT = 1,
#pPageSize INT = 10,
/*– Sorting Parameters */
#pSortColumn nvarchar(50) = 'FirstName',
#pSortOrder nvarchar(4)='ASC',
#pTotalCount int output
)
AS
BEGIN
/*–Declaring Local Variables corresponding to parameters for modification */
DECLARE
#lFirstName nvarchar(50),
#lLastName nvarchar(50),
#lEmail nvarchar(255),
#lLocation nchar(10),
#lPhoneNumber nvarchar(50),
#lPseudoName nvarchar(500),
#lPageNbr INT,
#lPageSize INT,
#lSortCol NVARCHAR(50),
#lFirstRec INT,
#lLastRec INT,
#lTotalRows INT,
#TotalCount INT
/*Setting Local Variables*/
SET #lFirstName = LTRIM(RTRIM(#pFirstName))
SET #lLastName = LTRIM(RTRIM(#pLastName))
SET #lEmail = LTRIM(RTRIM(#pEmail))
SET #lLocation = LTRIM(RTRIM(#pLocation))
SET #lPhoneNumber = LTRIM(RTRIM(#pPhoneNumber))
SET #lPseudoName = LTRIM(RTRIM(#pPseudoName))
SET #lPageNbr = #pPageNo
SET #lPageSize = #pPageSize
SET #lSortCol = LTRIM(RTRIM(#pSortColumn))
SET #lFirstRec = ( #lPageNbr - 1 ) * #lPageSize
SET #lLastRec = ( #lPageNbr * #lPageSize + 1 )
SET #lTotalRows = #lFirstRec - #lLastRec + 1
; WITH User_Results
AS (
SELECT ROW_NUMBER() OVER (ORDER BY
CASE WHEN (#lSortCol = 'FirstName' AND #pSortOrder='ASC')
THEN U1.FirstName
END ASC,
CASE WHEN (#lSortCol = 'FirstName' AND #pSortOrder='DESC')
THEN U1.FirstName
END DESC,
CASE WHEN (#lSortCol = 'LastName' AND #pSortOrder='ASC')
THEN U1.LastName
END ASC,
CASE WHEN #lSortCol = 'LastName' AND #pSortOrder='DESC'
THEN U1.LastName
END DESC,
CASE WHEN #lSortCol = 'Email' AND #pSortOrder='ASC'
THEN U1.Email
END ASC,
CASE WHEN #lSortCol = 'Email' AND #pSortOrder='DESC'
THEN U1.Email
END DESC,
CASE WHEN #lSortCol = 'Location' AND #pSortOrder='ASC'
THEN U1.LocationID
END ASC,
CASE WHEN #lSortCol = 'Location' AND #pSortOrder='DESC'
THEN U1.LocationID
END DESC,
CASE WHEN #lSortCol = 'PhoneNumber' AND #pSortOrder='ASC'
THEN U1.PhoneNumber
END ASC,
CASE WHEN #lSortCol = 'PhoneNumber' AND #pSortOrder='DESC'
THEN U1.PhoneNumber
END DESC,
CASE WHEN #lSortCol = 'PseudoName' AND #pSortOrder='ASC'
THEN U1.PseudoName
END ASC,
CASE WHEN #lSortCol = 'PseudoName' AND #pSortOrder='DESC'
THEN U1.PseudoName
END DESC
) AS ROWNUM,
Count(*) over () AS TotalCount,
U1.ID,
U1.FirstName,
U1.LastName,
U1.Email,
DPD.Value as Location,
U1.PhoneNumber,
U2.FirstName+' '+U2.LastName as ReportTo,
U1.PseudoName,
U1.IsActive,
US.ID AS SId,
US.SkillID AS SkillId,
UR.ID AS RId,
UR.RoleID AS RoleId,
U1.Created,
U1.Deleted
FROM dwd.[User] U1 with (nolock)
INNER JOIN dwd.[User] U2 with (nolock) ON U2.ID=U1.ReportTo
INNER JOIN dwd.[DomainParameterDetail] DPD with (nolock) ON DPD.ID=U1.LocationID
INNER JOIN dwd.[UserSkill] US WITH(NOLOCK) ON U1.ID = US.UserID
INNER JOIN dwd.[UserRole] UR WITH(NOLOCK) ON U1.ID = UR.UserID
WHERE
(#lFirstName IS NULL OR U1.FirstName = #lFirstName)
AND(#lLastName IS NULL OR U1.LastName LIKE '%' + #lLastName + '%')
AND(#lEmail IS NULL OR U1.Email LIKE '%' + #lEmail + '%')
AND (#lLocation IS NULL OR U1.LocationID LIKE '%' + #lLocation + '%')
AND (#lPhoneNumber IS NULL OR U1.PhoneNumber = #lPhoneNumber)
AND (#lPseudoName IS NULL OR U1.PseudoName LIKE '%' +#lPseudoName+ '%')
AND U1.IsActive=1 AND U1.Deleted=0 AND U1.ApplicationClientID=#pApplicationClientID
AND U1.ID<>1
)
SELECT
TotalCount,
ROWNUM,
ID,
FirstName,
LastName,
Email,
Location,
PhoneNumber,
ReportTo,
PseudoName,
IsActive,
S
Id,
SkillId,
RId,
RoleId,
Created,
Deleted
FROM User_Results AS USER_GET_RESULT
WHERE
ROWNUM > #lFirstRec
AND ROWNUM < #lLastRec
ORDER BY ROWNUM ASC
Select #TotalCount = Count(*) from dwd.[User]
WHERE IsActive=1 AND Deleted=0 AND ID<>1
Set #pTotalCount = #TotalCount
END
SO I have to get this donw in where clause of SP.

Answer 1

This is a bit long for a comment.
You can only do what you want using dynamic SQL. But, that seems entirely unnecessary, because all the comparisons use LIKE. So, it is better to write the function as:
CREATE FUNCTION dwd.GetSearchCriteria (
#pValue NVARCHAR(50),
#pCriteriaOption NVARCHAR(3)
)
RETURNS varchar(2000)
AS
BEGIN
declare #LIKEPATTERN varchar(2000) ;
SET #LIKEPATTERN = (CASE WHEN #PValue IS NULL THEN ''''''
WHEN #pCriteriaOption = 'ST' THEN '''' + #pValue + '%'''
WHEN #pCriteriaOption = 'ET' THEN '''' + '%' + #pValue + ''''
WHEN #pCriteriaOption = 'CT' THEN '''%' + #pValue + '%'''
ELSE ''''''
END)
RETURN #LIKEPATTERN
END ;
Note: Using an IF and CASE is redundant. The logic can be combined into a single expression. I also think return types should match the type of the variable being returned.
Then you can express the call as:
DECLARE #LIKEPATTERN varchar(2000);
SET #LIKEPATTERN = dwd.GetSearchCriteria('A','ET');
SELECT FirstName FROM dwd.[User] WHERE FirstName LIKE #LIKEPATTERN;