I am the creator of one of the biggest free online collections of articles on a single topic, with his 50-part series on SQL Server Always On Availability Groups.īased on my contribution to the SQL Server community, I have been recognized as the prestigious Best Author of the Year continuously in 2019, 2020, and 2021 (2nd Rank) at SQLShack and the MSSQLTIPS champions award in 2020. I published more than 650 technical articles on MSSQLTips, SQLShack, Quest, CodingSight, and SeveralNines. I am the author of the book " DP-300 Administering Relational Database on Microsoft Azure". Hi! I am Rajendra Gupta, Database Specialist and Architect, helping organizations implement Microsoft SQL Server, Azure, Couchbase, AWS solutions fast and efficiently, fix related issues, and Performance Tuning with over 14 years of experience. The following command removes column from the table. We can use Alter table command to remove a column as well. SQL DELETE columns using the T-SQL table designer You can either save it by pressing CTRL + S or close the table designer and click Yes on the following window. Right-click on the left-hand side of a column and you get option Delete Column. It shows all column of a particular table. Right-click on the table and go to Design. We can use it to delete a column from an existing table as well. We use the table designer in SSMS to define required columns, data types, and column properties such as primary key, identity columns. SQL DELETE columns using SSMS table designer Click Ok, and it removes the column from the table. It opens a window and lists the column name to remove. Right-click on the column we want to remove and click on Delete as shown in the following image. It shows all the columns of the particular table. In the particular database, locate the particular table and expand the columns. Connect to an instance in SSMS, expand databases. We can remove a column using the Graphical User Interface (GUI) method in SQL Server. SQL DELETE column using SSMS object explorer Let’s explore how to remove a column from an existing SQL table. Here, I intend that you should perform database clean up and remove the unwanted columns to improve query performance as well. It can help you to save the network bandwidth as well. Bytes sent to the client, Bytes received from the server, client processing time and total processing time for the query that does not contain the column. You can note a significant reduction in the TDS packets received from the server. Similarly, compare the client statistics of both queries. The query optimizer and SQL database engine require to put an additional effort for this column while it is not useful to retrieve data from it. You see low values of compiled memory, CPU time, reduced wait counts. You can notice that query without the column provides improved performance. Let’s compare the actual execution plan of both queries in SSMS. This table contains 4 million rows, and the user executed the command to select all records from this table.įROM. Below is my table structure and we need to remove column having data type varchar(2000). Let’s understand why it is essential to remove unwanted columns from the SQL table. We implemented a separate mechanism to capture product feedback, and this column is not relevant now. For example, consider a product table, and in this table, you have a column. There are specific columns in this table that are not relevant now. Suppose you have an existing table with multiple columns. You can refer to article – What is Database Normalization in SQL Server? We do not cover normalization techniques in this article. We have multiple normalization forms specified in the following image. It helps to reduce the redundancy and dependency of data. In a relational database, we use the schema design technique Normalizations and split the large tables into smaller tables. We will also understand the impact of removing a column with defined constraints and objects on it. In this article, we will explore the process of SQL Delete column from an existing table.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |