UPDATE Statement:

Modifies existing data in a table.

UPDATE [table name ]

SET [column name ]

= CASE

 WHERE condition;

UPDATE [employees]

 SET [department ]

=Case

WHERE last name = ‘James’ THEN ‘Data Analytics’

HOW TO UPDAT SINGLE INFO FROM A COLUMN IN A TABLE WITHOUT AFFECTING OTHER INFO

UPDATE [table name]

SET [table name].the Header of the line you want to replace = new info

WHERE [table name].header = ‘Unique identifier’

Example

UPDATE [dbo].[Pupils_information]

SET [dbo].[Pupils_information].Age = 11

WHERE [dbo].[Pupils_information].Name = ‘Martins Ogbodo’

DELETE Statement:

Deleting a column in SQL is one of the most common operations when dealing with a database. For this reason, knowing how to properly delete a column in SQL is critical. Without the right procedures and precautions, you could run into data integrity and data loss issues.

What Does it Mean to Delete a Column in SQL?In SQL, deleting a column refers to the process of permanently removing a specific column from a table. All data associated with the column will be removed from the disk. Similarly, the column’s metadata will be removed from the table’s schema. When you delete a column, you essentially eliminate its existence within the table structure. The column will be no longer available for queries and its data will be lost.

DELETE FROM [table name] WHERE condition;

Example:

WHERE last name = ‘Paul’;

To delete a column

Alter Table[Table Name]

Drop column[column name]