Page 479 - Computer_Science_F5

Computer Science in a table, use the following syntax ALTER TABLE table_name DROP COLUMN
column_name; For example - We need to delete ParentName from the student_
registration table; the command will be: ALTER TABLE student_registration DROP
COLUMN ParentName; To modify a column data type in a table, use the following
syntax ALTER TABLE table_name MODIFY COLUMN column_name datatype;
FOR ONLINE READING ONLY
(c) DROP
The drop command is used to delete both the table structure and the record stored
in the table. The syntax is DROP TABLE table_name; For example: If you want
to delete table student_registration, the command will be DROP TABLE student_
registration. This will delete the table and its contents.

(d) TRUNCATE
It is used to delete all rows in the table. The syntax is TRUNCATE TABLE table_
name; For example: If you have to delete the rows in the student_registration table,
you need to write TRUNCATE TABLE student_registration;

Data Manipulation Language (DML) commands
DML commands are used to modify the database. Those commands are responsible
for all forms of CHANGES in the database. The command of DML is not auto-
committed, which means it cannot permanently save all the changes in the database.
They can be rolled back. DML involves INSERT, UPDATE, and DELETE commands.

(a) INSERT
The INSERT command is used to add new records to the table. The syntax is INSERT
INTO table_name (column1, column2, column3, ...) VALUES (‘value1’, ‘value2’,
‘value3’, ...); Example: Insert students’ data in the student_registration table with
column (studentID, FirstName, MiddleName, LastName, Address).

An example of an INSERT query
INSERT INTO student_registration (StudentID, FirstName, MiddleName, LastName,
Address) VALUES (`1234`,‘Mwakalinga’, ‘Mwakatope’, ‘Mkinga’, ‘972 Mbeya’);
Also, see the query in Figure 8.21.

Figure 8.21: The INSERT query

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Computer Science Form 5.indd 470 23/07/2024 12:34