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SQL Server Table Contd- Columns

 Add the new column in SQL server table

              Once we have created the tables, all applications will used to store the details in the tables so we cant use the create table along with data. We can add the column in two ways in SSMS SQL server.

1.       Using the SSMS Object Explorer Design Option

2.       Using the ALTER keyword we can add the new column in SQL serve Table

                            Syntax                

ALTER TABLE TableName

 

ADD Column1 Datatype1,Colun2 Datatype2

Example

ALTER TABLE dbo.Student

 

ADD EMailID VARCHAR(50) NULL,FatherName VARCHAR(80)

             

              Please refer the below link:

                             https://learn.microsoft.com/en-us/sql/relational-databases/tables/add-columns-to-a-table-database-engine?view=sql-server-ver16

 

Delete column in a SQL server table

              Once we have created the tables, we might need to delete the column which is not required any more. We can use the following ways to delete the table.

1.       Using the SSMS Object Explorer Design Option

2.       Using the ALTER and DROP keyword we can add the new column in SQL serve Table

                            Syntax                

ALTER TABLE TableName

 

DROP COLUMN Column1

Example

ALTER TABLE dbo.Student

 

DROP COLUMN EMailID

             

              Please refer the below link:

                             https://learn.microsoft.com/en-us/sql/relational-databases/tables/delete-columns-from-a-table?view=sql-server-ver16

 Rename the column in a SQL server table

              Once we have created the tables, we might need to change the column name which will help to give meaningful. We can use the following ways to rename the table column name.

1.       Using the SSMS Object Explorer Design and Table Design Option

2.       Using the pre-defined Stored procedure available in SQL server

                            Syntax                

 

 EXEC sp_rename

'Fully Qualified Column Name', 'new column name', 'COLUMN';

Example

EXEC sp_rename 'dbo.Student.FatherName', 'FatherFullName', 'COLUMN';

       While running the query system will throw the caution message. Please make sure we haven’t used this name any dependent objects of SQL server.

              Please refer the below link:

                             https://learn.microsoft.com/en-us/sql/relational-databases/tables/rename-columns-database-engine?view=sql-server-ver16

 Modify the column in a SQL server table

              Modifying column will help us to change the column data type or increase the length of the data type which is required if the application usage increased or if we wrongly specified the column details. We can use the following ways to rename the table column name.

1.       Using the SSMS Object Explorer Table Design Option

2.       Using the ALTER keyword we can modify the table column.

                            Syntax                

              ALTER TABLE TableName

 

ALTER COLUMN ColunName VARCHAR(150) NOT NULL

Example

ALTER TABLE dbo.Student

 

ALTER COLUMN FatherFullName VARCHAR(150) NOT NULL

                     Here I am changing the column length and adding NOT NULL condition using alter.

              Please refer the below link:

                             https://learn.microsoft.com/en-us/sql/relational-databases/tables/modify-columns-database-engine?view=sql-server-ver16

 Setting Default Value to the column

              Instead of insert the NULL value in column value we can insert the default value for the column. We can use default parameter while you want to insert the system date in the table

Using the Default keyword we can add the default value in SQL server.

                            Example while create

  CREATE TABLE dbo.doc_exz (

      column_a INT,

      column_b INT DEFAULT 50);

While Alter Table

ALTER TABLE dbo.doc_exz

  ADD CONSTRAINT DF_Doc_Exz_Column_B

  DEFAULT 50 FOR column_b;

Generally Default value is a one of the SQL server constraint. So we can give the specific name for the same. Please refer the below

                            CREATE TABLE dbo.doc_exz (

                column_a INT,

             column_b INT CONSTRAINT DF_Doc_Exz_Column_B DEFAULT 50);

               Please refer the below link:

                             https://learn.microsoft.com/en-us/sql/relational-databases/tables/specify-default-values-for-columns?view=sql-server-ver16

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