IsNull function in DB2 SQL?

问题:

Is there a performant equivalent to the isnull function for DB2?

Imagine some of our products are internal, so they don't have names:

Select product.id, isnull(product.name, "Internal) 
From product

Might return:

1 Socks 
2 Shoes 
3 Internal 
4 Pants

回答1:

For what its worth, COALESCE is similiar but

IFNULL(expr1, default)

is the exact match you're looking for in DB2.

COALESCE allows multiple arguments, returning the first NON NULL expression, whereas IFNULL only permits the expression and the default.

Thus

SELECT product.ID, IFNULL(product.Name, "Internal") AS ProductName
FROM Product

Gives you what you're looking for as well as the previous answers, just adding for completeness.

回答2:

I'm not familiar with DB2, but have you tried COALESCE?

ie:

SELECT Product.ID, COALESCE(product.Name, "Internal") AS ProductName
FROM Product

回答3:

Select Product.ID, VALUE(product.Name, "Internal") AS ProductName from Product

回答4:

In DB2 there is a function NVL(field, value if null).

Example:

SELECT ID, NVL(NAME, "Internal) AS NAME, NVL(PRICE,0) AS PRICE FROM PRODUCT WITH UR;

回答5:

I think COALESCE function partially similar to the isnull, but try it.

Why don't you go for null handling functions through application programs, it is better alternative.

回答6:

COALESCE function same ISNULL function Note. you must use COALESCE function with same data type of column that you check is null.

回答7:

hope this might help someone else out there

  SELECT 
.... FROM XXX XX
WHERE
....
AND(
       param1 IS NULL
       OR XX.param1 = param1
       )