Update con un case sql

After the SET keyword, we specified the column names to be updated, and also, we matched them with the referenced table columns. After the FROM clause, we retyped the table name, which will be updated. In addition to this, we can specify a WHERE clause and filter any columns of the referenced or updated table.

We can also rewrite the query by using aliases for tables. Indexes are very helpful database objects to improve query performance in SQL Server. Particularly, if we are working on the performance of the update query, we should take into account of this probability. The following execution plan illustrates an execution plan of the previous query. The only difference is that this query updated the 3. This query was completed within 68 seconds. We added a non-clustered index on Persons table before to update and the added index involves the PersonCityName and PersonPostCode columns as the index key.

The following execution plan is demonstrating an execution plan of the same query, but this query was completed within seconds because of the added index, unlike the first one.

We have seen this obvious performance difference between the same query because of index usage on the updated columns. As a result, if the updated columns are being used by the indexes, like this, for example, the query performance might be affected negatively.

In particular, we should consider this problem if we will update a large number of rows. To overcome this issue, we can disable or remove the index before executing the update query.

On the other hand, a warning sign is seen on the Sort operator, and it indicates something does not go well for this operator. When we hover the mouse over this operator, we can see the warning details. Sign up or log in Sign up using Google.

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Podcast Making Agile work for data science. Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Visit chat. Understanding Thread Starvation in. NET Core Applications. Exploring Numeric Streams In Java. What Is The Metaverse. Microservice Circuit Breaker Pattern. We have updated state code column using CASE expression.

I hope that you will get an idea about how to use CASE expression. I hope you will enjoy these tips while playing with SQL Server. I would like to have feedback from my blog readers.