Cursors can be faster than a while loop but they do have more overhead. The cursors are slower because they update tables row by row. The following example explains the replacement of cursors through joins. Next Recommended Reading. Windows 10 Vs Windows Visual Studio Vs Visual Studio Understanding Matplotlib With Examples.
Understanding Numpy With Examples. C Evolution. This is how I see it:. They were popular before some new options were added to SQL Server. Better spend some time investigating and learning something new, and finally, producing optimal code. FROM city. END ;. In relational databases, operations are made on a set of rows. Sometimes the application logic needs to work with a row at a time rather than the entire result set at once. If you possess programming skills, you would probably use a loop like FOR or WHILE to iterate through one item at a time, do something with the data and the job is done.
But be advised, take this path and trouble may follow. Below, we will show some examples where using a CURSOR creates performance issues and we will see that the same job can be done in many other ways. After a short coffee break, the query finished executing, returning rows in the time shown below.
In the cursor execution, we have two steps. Step one, the positioning, when the cursor sets its position to a row from the result set. Step two, the retrieval, when it gets the data from that specific row in an operation called the FETCH. These operations are repeated until there are no more rows to work with. Our demo tables are relative small containing roughly 1, and rows. I hope after reading this article you will be able to understand cursors in SQL Server.
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