Q: Which MySQL command is used to modify the structure of a table?
A. ALTER TABLE
B. UPDATE TABLE
C. MODIFY TABLE
D. CHANGE TABLE
Correct Option: AExplanation:
The ALTER TABLE command is used in MySQL to modify the structure of an existing table. It can be used to add or remove columns, change column data types, modify constraints, and perform other table alterations.
Q: Which MySQL statement is used to delete a table from a database?
A. DROP TABLE
B. DELETE TABLE
C. REMOVE TABLE
D. ERASE TABLE
Correct Option: AExplanation:
The DROP TABLE statement is used in MySQL to delete an existing table from a database. It permanently removes the table and all its associated data.
Q: What is the purpose of the ORDER BY clause in a MySQL query?
A. To specify the columns to retrieve
B. To sort the result set
C. To filter the rows based on conditions
D. To group the rows into subsets
Correct Option: BExplanation:
The ORDER BY clause in a MySQL query is used to sort the result set based on one or more columns. It allows you to specify the sorting order (ascending or descending) for each column.
Q: Which statement is used to create a new database in MySQL?
A. CREATE TABLE
B. INSERT INTO
C. CREATE DATABASE
D. SELECT FROM
Correct Option: CExplanation:
The CREATE DATABASE statement is used in MySQL to create a new database. It specifies the name of the database that you want to create and any additional options such as character set and collation.
Q: Which MySQL data type is used to store a date and time value?
A. INT
B. VARCHAR
C. DATE
D. BOOLEAN
Correct Option: CExplanation:
The DATE data type in MySQL is used to store a date value without any time components. It allows you to store dates in the format 'YYYY-MM-DD'.
Q: Which MySQL command is used to update existing records in a table?
A. MODIFY
B. ALTER
C. UPDATE
D. CHANGE
Correct Option: CExplanation:
The UPDATE command is used in MySQL to modify existing records in a table. It allows you to specify the columns to be updated and the new values to be assigned.
Q: Which MySQL statement is used to grant privileges to a user account?
A. CREATE USER
B. GRANT
C. ALLOW
D. ENABLE
Correct Option: BExplanation:
The GRANT statement is used in MySQL to grant privileges to a user account. It allows you to specify the privileges (such as SELECT, INSERT, UPDATE, DELETE) and the objects (tables, databases) on which the privileges are granted.
Q: What is the purpose of the INDEX in a MySQL database?
A. To define a primary key for a table
B. To ensure data integrity
C. To optimize query performance
D. To enforce referential integrity
Correct Option: CExplanation:
In MySQL, an INDEX is used to optimize the performance of queries by creating a data structure that allows for faster data retrieval. It helps in speeding up the search, sorting, and joining of tables.
Q: Which MySQL function is used to calculate the total number of rows in a table?
A. COUNT()
B. SUM()
C. AVG()
D. MAX()
Correct Option: AExplanation:
The COUNT() function in MySQL is used to calculate the total number of rows in a table. It can be used with or without specifying a column, and it returns the count of non-null values.
Q: What is the purpose of the WHERE clause in a MySQL query?
A. To specify the columns to retrieve
B. To sort the result set
C. To filter the rows based on conditions
D. To group the rows into subsets
Correct Option: CExplanation:
The WHERE clause in a MySQL query is used to filter the rows from a table based on specified conditions. It allows you to retrieve only the rows that satisfy the given criteria.
Introduction to MySQL Databases - Quiz