PostList

MS SQL Advice - COUNT(*) vs EXISTS

MS SQL Advice - COUNT(*) vs EXISTS

If you want to check for data existence in a table (e.g. if there are invoices on a concrete date) you could use COUNT(*) or the EXISTS statement. I found various theories on the internet and even in some SQL books what is the best approach, so I decided to test this by myself (spoiler alert: the books are on the side of using EXISTS)....

Read More
MS SQL Advice - Use constraints

MS SQL Advice - Use constraints

Why you should use constraints on your tables? Except the fact that you should use constraints to check your data and the integrity of them (e.g. only allow inserting of numeric value between 1 and 5 for storing vote value) you could use them also for better query executions and get some performance boost. Let’s find how....

Read More