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WorksheetsDAY 22 MySQL: Constraints, Normalization (9th JULY 24)
Total questions: 10
Worksheet time: 5mins
Which query adds a primary key constraint to the 'id' column
in the 'students' table?
ALTER TABLE students ADD CONSTRAINT PRIMARY
KEY (id);
ALTER TABLE students ADD PRIMARY KEY (id);
UPDATE TABLE students SET PRIMARY KEY (id);
MODIFY TABLE students SET PRIMARY KEY (id);
Which query creates a table 'enrollments' with a foreign key
constraint referencing 'students' ?
CREATE TABLE enrollments (student_id INT, course_id
INT, FOREIGN KEY (student_id) REFERENCES
students(id));
CREATE TABLE enrollments (student_id INT, course_id
INT, SET FOREIGN KEY (student_id) TO students(id));
CREATE TABLE enrollments (student_id INT, course_id
INT, ADD FOREIGN KEY (student_id) REFERENCES
students(id));
CREATE TABLE enrollments (student_id INT, course_id
INT, ADD CONSTRAINT FOREIGN KEY (student_id)
REFERENCES students(id));
Which query removes a unique constraint from the 'email'
column in the 'students' table?
ALTER TABLE students DROP UNIQUE (email);
ALTER TABLE students REMOVE UNIQUE (email);
ALTER TABLE students DELETE UNIQUE (email);
ALTER TABLE students DROP CONSTRAINT UNIQUE
(email);
Which query sets a default value of 'Active' for the 'status'
column in the 'students' table?
ALTER TABLE students SET DEFAULT 'Active' FOR
status;
ALTER TABLE students CHANGE DEFAULT 'Active' FOR
status;
ALTER TABLE students MODIFY status SET DEFAULT
'Active';
ALTER TABLE students ALTER COLUMN status SET
DEFAULT 'Active';
Which query ensures that the 'age' column in the 'students'
table cannot have null values?
ALTER TABLE students SET NOT NULL (age);
ALTER TABLE students MODIFY age NOT NULL;
ALTER TABLE students ALTER COLUMN age SET NOT
NULL;
ALTER TABLE students UPDATE age SET NOT NULL;
Which normalization form ensures that all non-key attributes
are fully functional dependent on the primary key?
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF)
Which query removes the foreign key constraint from the
'student_id' column in the 'enrollments' table?
ALTER TABLE enrollments DROP FOREIGN KEY
(student_id);
ALTER TABLE enrollments REMOVE FOREIGN KEY
(student_id);
ALTER TABLE enrollments DROP CONSTRAINT
FOREIGN KEY (student_id);
ALTER TABLE enrollments DROP CONSTRAINT
student_id;
Which query creates a table 'courses' with a unique constraint
on the 'course_code' column?
CREATE TABLE courses (course_id INT, course_name
VARCHAR(100), course_code VARCHAR(20) UNIQUE);
CREATE TABLE courses (course_id INT, course_name
VARCHAR(100), UNIQUE course_code VARCHAR(20));
CREATE TABLE courses (course_id INT, course_name
VARCHAR(100), ADD UNIQUE (course_code)
VARCHAR(20));
CREATE TABLE courses (course_id INT, course_name
VARCHAR(100), SET UNIQUE (course_code));
Which normalization form ensures that there are no transitive
dependencies in a table?
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF)
Which query adds a check constraint to ensure the 'age'
column in the 'students' table is always greater than 18?
ALTER TABLE students ADD CONSTRAINT age_check
CHECK (age > 18);
ALTER TABLE students SET CONSTRAINT CHECK (age
> 18);
ALTER TABLE students ADD CHECK (age > 18);
ALTER TABLE students MODIFY CHECK (age > 18);
