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I'd like to write a SELECT statement that uses just one test to return columns with no value (null, empty, or all spaces). I thought this would work: SELECT column_name from table_name WHERE column_name NOT LIKE '%_%';
Can anyone point out how to check if a select query returns non empty result set? For example I have next query: SELECT * FROM service s WHERE s.service_id = ?; Should I do something like next: ISNULL(SELECT * FROM service s WHERE s.service_id = ?) to test if result set is not empty?
Solutions. MySQL. The MySQL IFNULL() function lets you return an alternative value if an expression is NULL: SELECT ProductName, UnitPrice * (UnitsInStock + IFNULL (UnitsOnOrder, 0)) FROM Products; or we can use the COALESCE() function, like this: SELECT ProductName, UnitPrice * (UnitsInStock + COALESCE(UnitsOnOrder, 0)) FROM Products; SQL Server.
6 cze 2024 · The ISNULL function in MS SQL takes two arguments: the first is a value or column name, and the second is the default value if the first argument is null. This query retrieves rows where the code column is either null, an empty string, or contains only spaces.
30 sie 2012 · NVL(expr1, expr2) If expr1 contains a NULL value, then replace it with the value of expr2. The NVL function lets you substitute a value when a null value is encountered. Examples: NVL (‘A’,’B’) results in A. NVL (NULL,’B’) results in B. NVL (1,2) results in 1. NVL (NULL,2) results in 2. NVL (‘A’,2) results in A.
To check if a value is NULL or not, you should use the IS NULL operator as follows: expression | column IS NULL Code language:SQL (Structured Query Language)(sql) The IS NULL operator returns true if the expression or column is NULL. Otherwise, it returns false.
The first statement inserts a record with a supplier_name that is null, while the second statement inserts a record with an empty string as a supplier_name. Now, let's retrieve all rows with a supplier_name that is an empty string value as follows: select * from suppliers where supplier_name = '';
