Pl sql case when is not null

Should I allow a null value to be passed here? Then take the necessary steps to bulletproof your code from nulls see last section in this blog post for details. When a row is inserted into and updated in this table, the following columns cannot be set to NULL :. Wait, you might be saying: Why do you have to provide a value for ID?

That's because identity columns can never be set to NULL. Identity columns are new to That behavior is shown in the code below. Instead, you must use a datatype that cannot be null or add code to your subprogram to "protect" it from null values. See the section Bulletproofing for Nulls below. Oracle Database currently treats a character value with a length of zero as null.

However, this may not continue to be true in future releases, and Oracle recommends that you do not treat empty strings the same as nulls. But we encourage you to not write code that assumes that this will always be the case. Whenever you declare a variable, it's value is set to NULL — unless you assign a different value to it. So, yes, you could do the following:. But I suggest that you do not. Don't worry; Oracle is never going to change this behavior, so you don't have to "take out insurance.

Study this Truth Table and make sure you are comfortable with everything you see in it. You can even verify it to yourself with this LiveSQL script.

Notice that if x is null or y is null, then x AND y is always null. The most important thing to remember is that in almost every case if any part of your expression evaluates to NULL , the entire expression will evaluate to NULL. In addition, pay close attention to how you construct conditional statements and expressions, when an expression might evaluate to NULL. But what if you want to treat two NULL s as being equal when you compare two values?

Marcus in the comments below suggests creating an isEqual function that handles this for you. Here's the implementation of Marcus's isequal function for dates:. It is also a statement , albeit a ''no-op" no operation -it only passes control to the next statement.

Here are two examples. Null values can be a real pain. The selector values i. If the result of a selector value equals the result of the selector , then the associated sequence of statements executes and the CASE statement ends.

In addition, the subsequent selector values are not evaluated. Because the ELSE clause is optional, you can skip it. I want to return a value based on the combinations in two different fields. Answer: Yes, below is an example of a case statement that evaluates two different fields. While using this site, you agree to have read and accepted our Terms of Service and Privacy Policy. Please re-enable javascript in your browser settings. It is the value that you are comparing to the list of conditions.