In this step by step SQL Tutorial I will show you how to remove rows from a table . For the purpose of this tutorial I will use SQL Server 2012.
Other Versions of SQL Server:
- SQL Server 2012
- This blog post has been written using SQL Server 2012
- SQL Server 2008 / R2
- The examples we used should work in SQL Server 2008 and R2
- SQL Server 2005
- We suspect that this will work in SQL Server 2005 as well
Who is it for?
- People who would like to learn basics of using SQL DELETE
- Those who are preparing for Microsoft certifications and need to cover this topic.
Delete allows to remove rows from a table and you can write delete query with filters so you delete only the rows you want.
To better understand DELETE let's create a task that is close to real-life. In our story imagine you are a developer
that has been ask to clean your table before loading new data from spreadsheet. In the following example I will show you how you could solve your task.
DELETE using SSMS 2012
For this example I will use AdventureWorksDW2012 database, dbo.DatabaseLog table.
I retrieve all data (*) From dbo.DatabaseLog and check how many rows I have got now.
I use DELETE statement to remove all records from dbo.DatabaseLog. You can see that in the Messages window under my script is message saying that 112 rows was deleted.
Now I just check if my table is empty and you can see that all columns contain not data.
In the Object Explorer I go to AdventureWorksDW2012, dbo.DimCusomer.
I open the table and find CustomerKey for row Katie Glownia.
I check rows number for DimCusomer table
I type script to delete customer key 29485 and run my query
I get Message saing that 1 row was deleted sucessfully.
I can see that in the DimCustomer last row containg data about Katie Glownia is not existing.
I have 18484 rows in DimCustemer.
I hope that will help you