How to Delete a column and Add a new column to database

mysql> alter table [table name] drop column [column name];

mysql> alter table [table name] add column [new column name] varchar (20);

To delete a column in MySQL, you would use the ALTER TABLE statement followed by the DROP COLUMN keyword. Here’s the syntax:

sql
ALTER TABLE table_name
DROP COLUMN column_name;

Replace table_name with the name of your table and column_name with the name of the column you want to delete.

To add a new column, you would also use the ALTER TABLE statement, this time followed by the ADD COLUMN keyword. Here’s the syntax:

sql
ALTER TABLE table_name
ADD COLUMN new_column_name column_definition;

Replace table_name with the name of your table, new_column_name with the name of the new column, and column_definition with the data type and any additional attributes for the column, such as INT, VARCHAR, DATE, etc.

For example, to delete a column named old_column and add a new column named new_column of type VARCHAR(50) to a table named my_table, you would do:

sql
ALTER TABLE my_table
DROP COLUMN old_column;

ALTER TABLE my_table
ADD COLUMN new_column VARCHAR(50);

Remember to be cautious when altering tables, especially if they contain important data, as these operations can’t be undone. It’s a good idea to make backups before making significant changes.