not able to retrieve if the table column has null value - sql

Question

I have stored procedure to find customer, its working fine. If Customer_City_Name is null in the table then I am not able to retrieve the row. SP fails . how to do this
I have to get result even if Customer_City_Name or Customer_Country_Code IS NULL
EXEC findCustomer null,'%',null,null,
SP code:
CREATE PROCEDURE findCustomer
#customerNumber NVARCHAR(100),
#customerNamePattern NVARCHAR(35),
#customerCityNamePattern NVARCHAR(35),
#customerCountryCode NVARCHAR(5)
AS
BEGIN
DECLARE #SQL NVARCHAR(4000)
SET #SQL =
'
SELECT
c.Customer_Number,
c.Customer_Name,
c.Postal_Address_Identifier,
c.Customer_Street_Or_Road_Name,
c.Customer_City_Name,
c.Customer_Territory_Code,
c.Customer_Postal_Code,
c.Customer_Country_Code,
c.Telephone_Number,
c.Mobile_Telephone_Number,
c.Fax_Number,
c.Email_Address
FROM Customer c
WHERE c.Customer_Number LIKE ' +
CASE WHEN #customerNumber IS NOT NULL
THEN '''' + #customerNumber + ''''
ELSE 'c.Customer_Number'
END + '
AND c.Customer_Name LIKE ' +
CASE WHEN #customerNamePattern IS NOT NULL
THEN '''' + #customerNamePattern + ''''
ELSE 'c.Customer_Name'
END + '
AND c.Customer_City_Name LIKE ' +
CASE WHEN #customerCityNamePattern IS NOT NULL
THEN '''' +#customerCityNamePattern + ''''
ELSE 'c.Customer_City_Name'
END + '
AND c.Customer_Country_Code LIKE ' +
CASE WHEN #customerCountryCode IS NOT NULL
THEN '''' +#customerCountryCode + ''''
ELSE 'c.Customer_Country_Code'
END
EXEC sp_executesql #SQL

Answer 1

#user2218371 you should reconsider alternatives instead of dynamic SQL. anyway, this is an alternative code.
CREATE PROCEDURE findCustomer
#customerNumber NVARCHAR(100),
#customerNamePattern NVARCHAR(35),
#customerCityNamePattern NVARCHAR(35),
#customerCountryCode NVARCHAR(5)
AS
BEGIN
DECLARE #SQL NVARCHAR(4000)
SET #SQL =
'
SELECT
c.Customer_Number,
c.Customer_Name,
c.Postal_Address_Identifier,
c.Customer_Street_Or_Road_Name,
c.Customer_City_Name,
c.Customer_Territory_Code,
c.Customer_Postal_Code,
c.Customer_Country_Code,
c.Telephone_Number,
c.Mobile_Telephone_Number,
c.Fax_Number,
c.Email_Address
FROM Customer c
WHERE ' +
CASE WHEN #customerNumber IS NOT NULL
THEN ' c.Customer_Number LIKE ''' + #customerNumber + '''' +
CASE WHEN #customerNamePattern IS NOT NULL THEN ' AND ' ELSE '' END
ELSE ''
END +
CASE WHEN #customerNamePattern IS NOT NULL
THEN ' c.Customer_Name LIKE ''' + #customerNamePattern + '''' +
CASE WHEN #customerCityNamePattern IS NOT NULL THEN ' AND ' ELSE '' END
ELSE ''
END +
CASE WHEN #customerCityNamePattern IS NOT NULL
THEN ' c.Customer_City_Name LIKE ''' + #customerCityNamePattern + '''' +
CASE WHEN +#customerCountryCode IS NOT NULL THEN ' AND ' ELSE '' END
ELSE ''
END +
CASE WHEN #customerCountryCode IS NOT NULL
THEN ' c.Customer_Country_Code LIKE ''' + #customerCountryCode + ''''
ELSE ''
END
EXEC sp_executesql #SQL

Answer 2

When one of the fields is NULL, your WHERE clause looks like this:
WHERE c.Customer_Number LIKE c.Customer_Number
This is clearly intentional, since it is part of the CASE statements.
However, LIKE doesn't return true for a pair of NULL values. (NULL is not LIKE NULL.) This is pretty typical behavior for NULL. = does the same thing.
See this very simple SQL Fiddle for a demonstration: http://sqlfiddle.com/#!3/82a23/3/0.
Assuming I'm reading this correctly, you want to simply ignore the column's value when the procedure argument is NULL. In that case, you will need to adjust your query to leave out the clause entirely or put some always true expression in its place when the argument is NULL.
If you insist on sticking with your dynamic SQL building function (which you should not), try this for your CASE statements:
WHERE ' +
CASE WHEN #customerNumber IS NOT NULL
THEN 'c.Customer_Number LIKE ''' + #customerNumber + ''''
ELSE '0=0'
END + '

Answer 3

Null values cant be compared with any other value, that means you don't get a True or a False.
To work around this issue I use the ISNULL built in function that checks if the value is null, and if it is returns your default value.
You should apply this function to each column where a null value is an option.
http://msdn.microsoft.com/en-us/library/ms184325.aspx

Answer 4

brother, so your query mainly is to perform select function to search for existing customer info
try to modify your where condition as sample below
Select ....
From .....
WHERE (#Customer_Number is null or c.Customer_Number like #Customer_Number + '%')
AND (#customerNamePattern is null or c.Customer_Name like #customerNamePattern + '%' )
AND (#customerCityNamePatternis null or c.Customer_City_Name like #customerCityNamePattern+ '%' )
AND (#customerCountryCode is null or c.c.Customer_Country_Code like #customerCountryCode + '%' )

Answer 5

I have fixed this issue by doing this
AND ISnull(c.Customer_City_Name,'''') LIKE ' +
CASE WHEN #customerCityNamePattern IS NOT NULL
THEN '''' +#customerCityNamePattern + ''''
ELSE 'isnull (c.Customer_City_Name,'''')'
END + '
AND Isnull(c.Customer_Country_Code,'''') LIKE ' +
CASE WHEN #customerCountryCode IS NOT NULL
THEN '''' +#customerCountryCode + ''''
ELSE 'isnull(c.Customer_Country_Code , '''')'
END
1.Thanks to asafrob i have accepted your approach.
2. Thanks to devio In 'LIKE' operator needs to select 'NULL'(DB) values I got idea from
3.Thanks to jpmc26 -- > I like your answer .
Finally thanks to every one answered to my question