COUNT And NULL

Bert Wagner explains some of the trickiness of COUNT and NULL values in SQL Server:

One thing I see fairly often (and am occasionally guilty of myself) is using COUNT(DISTINCT) and DISTINCT interchangeably to get an idea of the number of unique values in a column.

While they will sometimes give you the same results, depending on the data the two methods may not always be interchangeable.

Click through for examples.

Related Posts

Pivoting Performance Counter Data

Dave Bland shows how you can build a dynamic pivot to see performance counter data over a stretch of time: The next step is to write the code to capture the counter values and insert the data it the temporary table created above.  Because we need to capture the values over a period of time, […]

Read More

Near-Zero Downtime Identity Column Changes

I’m getting close to the end of my series on near-zero downtime deployments. This latest post involves identity column changes: There are some tables where you create an identity value and expect to cycle through data. An example for this might be a queue table, where the data isn’t expected to live permanently but it […]

Read More

Categories

February 2019
MTWTFSS
« Jan Mar »
 123
45678910
11121314151617
18192021222324
25262728