confusion in Isnull and ' ' in sql query

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heyy..

I am confused with Isnull query ...

IN my table I have a field(customer Name) with a blank value......... when i write query like this..

SQL

select * from dbo.M_CustomerMasterDetails
where
CustomerMasterId=281 and (
 CustomerName = is null;
 PartyCode =is null)

I don't get the result ....

But when I write query link this..

SQL

select * from dbo.M_CustomerMasterDetails
where
CustomerMasterId=281 and (
 CustomerName = ''
 PartyCode ='')

I got result...

what is the diffrence b/w is null and ' ' in sql......

Posted 10-Jun-13 18:32pm

aravindnass

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SLNS001 11-Jun-13 0:38am

I think, we can't use NULL in where clause.

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_Damian S_ · Accepted Answer · 2013-06-10T18:38:00

Null means the value is unknown.

'' means that there is a value, and that it's an empty string.

If your database allows nulls for the CustomerName and PartyCode fields, you would need to check for them in your query. One option would be this:

SQL

select * from dbo.M_CustomerMasterDetails
where
CustomerMasterId= 281 and (
 isnull(CustomerName, '') = ''
 or isnull(PartyCode, '') = '')

As an aside, there are syntax errors in your queries above. That might account for some of your issues.