You should generally use EXISTS rather than forcing the server to perform a complete count if all that you care about are 0 and at least 1. Neither of those blocks of code are correct.
The first one won't even run. You'll get a syntax error. Why accept it? Why do you insist it works? With regards to the second piece of code: a count always returns something so it always 'exists'. Yes the first piece of code works now that you have edited it.
You might want to edit that bit now. Show 2 more comments. If there are zero records, nothing will be inserted by this code. McDermaid Nick. Add a comment. Sunil Kumar Sunil Kumar 1 1 gold badge 7 7 silver badges 12 12 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field.
Then, the field will be saved with a NULL value. A field with a NULL value is one that has been left blank during record creation! Select all records from the Customers where the PostalCode column is empty. We just launched W3Schools videos. However, this query cannot use the created non-clustered index so it will read all index pages and then return the appropriate rows.
To eliminate this situation, we can make a little code modification in the query so that the query optimizer can use the indexes more efficiently. The following query returns some rows as like the previous one but it uses the indexes more efficiently.
FROM Person. USE [ AdventureWorks ]. ON [ Person ]. Author Recent Posts. Esat Erkec. His current interests are in database administration and Business Intelligence. You can find him on LinkedIn. View all posts by Esat Erkec. Latest posts by Esat Erkec see all.
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