How to change column name and data type of a column cannot be done in one statement but first we need to change the column name and then data type, In this post we will check many other things like how to change data type of a column, how to drop a column, how to add a new column, how to make a column not nullable etc.
So first we will see how to change a column name as well as data type of the column, as I said we cannot do it in one statement but we first need to change the column name and then data type so let's see this:
Suppose we want to change the column
"BlogTypeID" to "Tags" from data type int to varchar(200) in Blogs table then
-- change column name BlogTypeID to Tags EXEC sp_rename 'blogs.BlogTypeID', 'Tags', 'COLUMN'
Once we will run this query we will get a warning "Caution: Changing any part of an object name could break scripts and stored procedures. It indicates that our existing procedures may break but our column name is changes, check the table.
Now we will alter the column data type
ALTER TABLE Blogs ALTER COLUMN Tags VARCHAR(200)
Now our task is completed to change column and column data type.
How to add a new column in a table
ALTER TABLE table_name ADD column_name datatype
To change the datatype to support 100 characters and make NOT NULL
ALTER TABLE table_name ALTER COLUMN column_name VARCHAR(100) NOT NULL
To change datatype and allow NULLs for column
ALTER TABLE table_name ALTER COLUMN column_name DATETIME NULL
To drop a column from a table
ALTER TABLE table_name DROP COLUMN column_name
Process manager with a reputed organization, Fond of learning new features and technology related to C#, ASP.Net, SQL Server, MVC etc.I like to help others, if I can
|By Hamden On 05 May, 13 Viewed: 1,875|
We can not directly change a column to identity columns, say we have a primary key column or any normal column in our table and want to make it identity column then we cannot do it directly by altering the table but there are only two way to change column to identity column 1. Create a new... By Ali Adravi On 02 May 2013 Viewed: 619
There are many ways which can help us to save our time to write some repeated code or to do some repeated action, in this post we will see some very common code which we need very frequently in our development life. I am not saying that after this post you will save your half say work every day but... By Ali Adravi On 31 Mar 2013 Viewed: 676
In SQL server there are decimal and money data type to store precision and scale both together or say decimal values. Suppose we want to get precision and scale separately then how to get it. There are many ways to do this but there is a function in SQL named PARSENAME which can be used to get... By Myghty On 26 Mar 2013 Viewed: 1,782
To write a good performing procedure or function we should be aware about available wildcards in SQL Server. I found most developer depends on ‘%’ wildcard only while we have others as well. In this article we will discuss all the available wildcards in detail with examples. First of all let’s see... By Dev D On 25 Feb 2013 Viewed: 458
When we need to concatenate two columns simply we can use `+` sign and that is correct, but what if any of them is null, Will it return what we want, NO, it will return null. So let's discuss how we should concatenate two or more columns without creating extra space or extra comma problem. Let's... By Ali Adravi On 13 Feb 2013 Viewed: 8,502