TIP: The DISTINCT Keyword is used to remove the Duplicates from the specified column Name.
Syntax expression IS [ NOT ] NULL Arguments. Determines whether a specified expression is NULL. NOT Specifies that the Boolean result be negated. SQL-Server shows a warning message, that NULLs are eliminated by AVG and COUNT.
And NULL will evaluate as UNKNOWN for these rather than the TRUE value. 2: But, if you want to count any string which consists of entire spaces as empty then use the WHERE clause like this : WHERE COLUMN <> '' The above code will not return NULL values when they are used in a WHERE clause. Note, because we are COUNTing x.CLAIM_ID, COUNT will return zero for NULL's, ie no claims for a specific date/status And the grouping/sorting GROUP BY … There's a situation in SQL Server where Declarative Referential Integrity (DRI) is not enforced because nulls are allowed in the table referencing the parent table. Transact-SQL Syntax Conventions. The predicate reverses its return values, returning TRUE if the value is not NULL, and FALSE if the value is NULL. First what field are you trying to count and second what fields are not null for that row. The SQL Server COUNT DISTINCT Column_Name returns the Unique number of rows present in the table whose values are NOT NULL (Ignores the NULL Records). The following example uses the COUNT(DISTINCT expression) to return the number of unique, non-null values in the t table: SELECT COUNT (DISTINCT val) val_count FROM t; The following shows the output: val_count ----- 5 Warning: Null value is eliminated by an aggregate or other SET operation.
If you are trying to actually count the nulls then here is a simple solution to that problem. «MAY HAVE» Referential Integrity. CREATE TABLE T ( C VARCHAR(10) ); INSERT INTO T
expression Is any valid expression. SQL Server COUNT(DISTINCT expression) example.