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The ALTER TABLE command adds, deletes, or modifies columns in a table. The ALTER TABLE command also adds and deletes various constraints in a table.

The ALTER TABLE statement in SQL is used to add, remove, or modify columns in an existing table. The ALTER TABLE statement is also used to add and remove various constraints on existing tables.

ALTER TABLE - ALTER/MODIFY DATATYPE SQL Server / MS Access: ALTER TABLE table_name. ALTER COLUMN column_name datatype; My SQL / Oracle (prior version 10G): ALTER TABLE table_name. MODIFY COLUMN column_name datatype; Oracle 10G and later: ALTER TABLE table_name. MODIFY column_name datatype;

The alter command is used when we want to modify a database or any object contained in the database. The drop command is used to delete databases from MySQL server or objects within a database. The rename command is used to change the name of a table to a new table name.

We can perform the following changes in a table schema by using the ALTER TABLE statement. Add a column in an existing table. Change datatype and length of the table. Add constraints in the table. Drop the existing table. Move table from default tablespace to different tablespace.

The SQL ALTER TABLE command is used to modify a table's structure by adding, deleting columns in an existing table. You can also use the ALTER TABLE command to add and drop various constraints on an existing table. Since this command modifies the structure of a table, it is a part of Data Definition Language.

The ALTER command in SQL is a DDL (Data Definition Language) statement which means that it is used for updating the structure of tables in a database. With the ALTER command, we can add, delete, or modify columns in an existing table.

To update data in a table, you need to:First, specify the table name that you want to change data in the UPDATE clause.Second, assign a new value for the column that you want to update.Third, specify which rows you want to update in the WHERE clause.

MySQL ALTER statement is used when you want to change the name of your table or any table field. It is also used to add or delete an existing column in a table. The ALTER statement is always used with "ADD", "DROP" and "MODIFY" commands according to the situation.

Explanation: Alter is used to modify an existing table, like adding a row or column.Changing a column datatype will result in conversion of existing data, which may result in data loss when there are errors such as overflows, under flows, or integrity constraint violations. Drop is used to remove a table completely.