Null strings in sql

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Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Linked Related Hot Network Questions. I need to compare two columns, and am hitting issues when comparing NULL against an empty string. Put simply, this is what I'm looking at. In this case, because we all know that an empty string and a null column value are different, I would hope to see the result come back as 'Pass', however it doesn't.

I know there must be a simply way around this that I'm missing If we use the ISNULL function to set null values to an empty string, then the comparison wont work as an empty string is equal to an empty string, for example.

This also returns 'FAIL', so this is a no go. I could always use ISNULL to convert this to a different string, but this still isn't suitable, as the empty string may have a different value which by chance could match whatever we decide to convert null values to. Your first example returns fail because you have the wrong operator. It is quicker and more "Pythonic" easier to understand by someone else who reads your code to evaluate to the same outcome on both sides of the equal sign:. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? This is perfect! If you are using MySq, use ifnull Column2, ''. CapelliC CapelliC Chris E Chris E 13 13 silver badges 26 26 bronze badges. Chris Chris 3, 1 1 gold badge 17 17 silver badges 26 26 bronze badges.

Chris Cooper Chris Cooper Adam, actually no-one had yet suggested the case expression as solution. I think your assessment is maybe too harsh.

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The course, among other, features over than 30 live demonstrations! Enroll Now with Discount! Even though the two functions are quite similar, still they have some differences:.

This was expected because that record does not contain a NULL value but an empty value instead. An empty value cannot be considered as a NULL of course. Additionally you can always create your own user-defined scalar-valued function that can deal with the issue of the empty string values. In my example, I created the following function and called it IsEmpty :.

My function takes as input two parameters; a the input string and b the replacement string. Though, the above user-defined function just handles strings and not any other expressions. Subscribe to our newsletter and stay up to date!

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