Learn MYSQL MCQs
Prepare MYSQL MCQs (Multiple choice Questions) for exam and job interviews.
How do you add a primary key to an existing table?
1) ALTER TABLE table_name ADD PRIMARY KEY (column_name);
2) MODIFY TABLE table_name ADD PRIMARY KEY (column_name);
3) SET PRIMARY KEY (column_name) IN table_name;
4) CREATE PRIMARY KEY column_name IN table_name;
Answer : Option 1
Which SQL command is used to remove duplicate rows?
1) DELETE DUPLICATES FROM table_name;
2) SELECT DISTINCT columns FROM table_name;
3) REMOVE DUPLICATES FROM table_name;
4) UNIQUE rows FROM table_name;
Answer : Option 2
What is the purpose of the MySQL command GROUP BY?
1) To aggregate data across multiple records
2) To sort records
3) To filter records
4) To limit results
Answer : Option 1
What data type is best for storing true/false values in MySQL?
1) TINYINT
2) BOOLEAN
3) BIT
4) YESNO
Answer : Option 1
Which operator is used to compare a value against a list of values?
1) BETWEEN
2) IN
3) LIKE
4) ANY
Answer : Option 2
How can you prevent duplicate entries in a MySQL column?
1) Using UNIQUE constraint
2) Using NOT NULL constraint
3) Using PRIMARY KEY
4) Using DEFAULT value
Answer : Option 1
Which function returns the number of rows in a MySQL table?
1) COUNT(*)
2) SUM(*)
3) TOTAL(*)
4) ROWS(*)
Answer : Option 1
What is the default port number for MySQL?
1) 3306
2) 5432
3) 8080
4) 1521
Answer : Option 1
What is the command to rename a column in a MySQL table?
1) ALTER TABLE table_name RENAME column_name TO new_column_name;
2) MODIFY TABLE table_name CHANGE column_name new_column_name;
3) RENAME COLUMN column_name TO new_column_name IN table_name;
4) CHANGE COLUMN column_name TO new_column_name IN table_name;
Answer : Option 2
How do you set a default value for a column in MySQL?
1) ALTER TABLE table_name MODIFY column_name SET DEFAULT value;
2) ALTER TABLE table_name CHANGE column_name SET DEFAULT value;
3) ALTER TABLE table_name ADD column_name DEFAULT value;
4) ALTER TABLE table_name MODIFY column_name SET value;
Answer : Option 1