WEEK 6

Question 1

Question: What is the purpose of the ALTER TABLE command?

Answer 1

Answer: The ALTER TABLE command is used to make changes in the table structure such as adding a column, modifying column characteristics, or deleting a column. It can also be used to add or remove table constraints.

Question 2

Question: What are the keywords used with the ALTER TABLE command?

Answer 2

Answer: The keywords used with the ALTER TABLE command are ADD, MODIFY, and DROP.

Question 3

Question: How is the data type and data characteristics of a column changed using the ALTER TABLE command?

Answer 3

Answer: The ALTER TABLE command is used to change the data type and characteristics of a column. The syntax for changing the data type is ALTER TABLE tablename MODIFY (columnname(datatype)). The syntax for changing the data characteristic is ALTER TABLE tablename MODIFY (columnname(characteristic)).

Question 4

Question: How is a column added using the ALTER TABLE command?

Answer 4

Answer: To add a column, the ALTER TABLE and ADD keywords are used. The NOT NULL clause is not included for the new column.

Question 5

Question: How is a column dropped using the ALTER TABLE command?

Answer 5

Answer: To drop a column, the ALTER TABLE and DROP keywords are used. Some RDBMSs impose restrictions on the deletion of an attribute.

Question 6

Question: What is the purpose of the UPDATE command?

Answer 6

Answer: The UPDATE command is used to update data in existing rows. If a relationship is established between entries and existing columns, the relationship can assign values to appropriate slots.