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MySQL mcq questions and answers | MySQL MCQs

Learn competitive MySQL mcq questions and answers with easy and logical explanations Page-9 section-1

Each section contains 100 MCQs on MySQL Miscellaneous .
81
Each database has a data directory located under database directory.
Discuss
Answer & Solution
Answer: Option B
Solution:
In MySQL, databases are organized within a directory structure on the filesystem. We need to determine whether each database has a data directory located under its respective database directory.

The correct answer is Option A: True.
82
The locking statements LOCK TABLES and UNLOCK TABLES are not permitted in stored routines.
Discuss
Answer & Solution
Answer: Option A
Solution:
In MySQL, locking statements such as LOCK TABLES and UNLOCK TABLES are used to control access to tables, preventing other sessions from modifying them while the lock is held. We need to determine whether these locking statements are permitted in stored routines.

The correct answer is Option A: True.
83
The following MySQL query belongs to which condition types?
SELECT fname
FROM person
WHERE title=’TELLER’;
Discuss
Answer & Solution
Answer: Option A
Solution:
Equality condition: This is the correct option. The condition in the query title='TELLER' specifies that the value in the "title" column must be exactly equal to 'TELLER'. It checks for equality between the column value and the specified constant value.
Inequality condition: This option is incorrect. Inequality conditions involve comparisons such as greater than, less than, greater than or equal to, or less than or equal to. The query provided does not involve any inequality comparisons.
Range condition: This option is incorrect. Range conditions involve specifying a range of values for comparison, such as between two constants or greater than a certain value. The provided query does not involve any range comparisons.
All of the mentioned: This option is incorrect. While the query involves an equality condition, it does not involve inequality or range conditions, so selecting "All of the mentioned" would be inaccurate.

Therefore, the correct answer is Option A: Equality condition, as the condition in the query checks for equality between the "title" column and the constant value 'TELLER'.
84
Deletion of an employee from table also deletes that employee from another table. This kind of delete is called . . . . . . . .
Discuss
Answer & Solution
Answer: Option D
Solution:
Transparent: This option is incorrect. "Transparent" does not describe a type of delete operation in MySQL. It does not specifically relate to deletion operations involving foreign key constraints.
Concrete: This option is incorrect. "Concrete" does not describe a type of delete operation in MySQL. It is not a term commonly used in database terminology regarding delete operations.
Elaborate: This option is incorrect. "Elaborate" does not describe a type of delete operation in MySQL. It is not a term commonly used in database terminology regarding delete operations.
Cascaded: This is the correct option. In MySQL, a cascaded delete refers to a delete operation that automatically triggers the deletion of related records in another table. It cascades the delete operation from the primary table to the related table, ensuring referential integrity and consistency in the database.

Therefore, the correct answer is Option D: cascaded, as it accurately describes the type of delete operation where deletion in one table cascades to related tables.
85
The default case sensitivity of the database and table names depends on . . . . . . . .
Discuss
Answer & Solution
Answer: Option B
Solution:
Server SQL mode: This is the correct option. The default case sensitivity of database and table names in MySQL is influenced by the SQL mode set for the server. The SQL mode determines various aspects of MySQL's behavior, including how it handles identifier case sensitivity. In certain SQL modes, such as ANSI_QUOTES, database and table names are treated as case-sensitive, while in others, such as IGNORE_SPACE, they are treated as case-insensitive.
Operating system of machine: This option is incorrect. The default case sensitivity of database and table names in MySQL is not determined by the operating system of the machine where MySQL is running. MySQL's behavior regarding case sensitivity is primarily controlled by server settings and SQL mode.
Does not depend on anything: This option is incorrect. The default case sensitivity of database and table names in MySQL does depend on certain factors, particularly the server SQL mode.
SQL server: This option is incorrect. The default case sensitivity of database and table names in MySQL is not determined by an external SQL server. It is determined by MySQL's own configuration and SQL mode settings.

Therefore, the correct answer is Option A: Server SQL mode, as it accurately reflects that the default case sensitivity of database and table names in MySQL is influenced by the server's SQL mode setting.
86
What is the default format for "Year" data type?
Discuss
Answer & Solution
Answer: Option A
Solution:
YYYY: This is the correct option. The default format for the "Year" data type in MySQL is YYYY, which represents a year value with four digits. For example, the year 2022 would be represented as '2022' when stored in a column with the "Year" data type.
YYYY-DD-MM: This option is incorrect. The "Year" data type does not include day or month components. It only represents a year value, so the format does not include day or month information.
MM-YYYY-DD: This option is incorrect. Similar to the previous option, this format includes day and month components, which are not applicable to the "Year" data type. It represents the month and day before the year, which is not the default format for the "Year" data type.
None of the mentioned: This option is incorrect. There is a default format for the "Year" data type in MySQL, which is YYYY. Therefore, the correct answer cannot be "None of the mentioned."

Therefore, the correct answer is Option A: YYYY, as it accurately represents the default format for the "Year" data type in MySQL.
87
Association between one or more MyISAM tables and the named key cache is set by . . . . . . . .
Discuss
Answer & Solution
Answer: Option B
Solution:
BEGIN: This option is incorrect. BEGIN is typically used to initiate a transaction in MySQL, not to associate MyISAM tables with the named key cache. It is used in the context of transactional operations rather than cache management.
CACHE INDEX: This is the correct option. The CACHE INDEX statement in MySQL is used to associate one or more MyISAM tables with the named key cache. By caching indexes, MySQL can improve the performance of queries that rely on those indexes. This statement allows you to specify which indexes should be cached, helping to optimize query execution.
ALTER DATABASE: This option is incorrect. ALTER DATABASE is used to modify the structure or properties of a database, such as changing its character set or collation. It is not directly related to caching indexes for MyISAM tables.
ALTER EVENT: This option is incorrect. ALTER EVENT is used to modify the definition of scheduled events in MySQL. It is not related to caching indexes for MyISAM tables.

Therefore, the correct answer is Option B: CACHE INDEX, as it accurately represents the command used to associate MyISAM tables with the named key cache in MySQL.
88
In the following SQL code, InnoDB is . . . . . . . .
CREATE TABLE student (
		name CHAR(30),
		student_id INT,
		PRIMARY KEY (student_id)
	) ENGINE = InnoDB;
Discuss
Answer & Solution
Answer: Option D
Solution:
In the provided SQL code snippet, the keyword "ENGINE" is used to specify the storage engine for the MySQL table being created. We need to identify what "InnoDB" represents in this context.

The correct answer is Option D: storage engine.

Database name: This option is incorrect. "InnoDB" does not refer to a database name in this context. It is related to the configuration of the table's storage engine.
Table name: This option is incorrect. "InnoDB" does not represent a table name in the provided SQL code. It specifies the storage engine to be used for the table.
Reference engine: This option is incorrect. "InnoDB" is not used as a reference engine in this context. It specifies the storage engine to be employed for the table.
Storage engine: This is the correct option. InnoDB is a storage engine used in MySQL. When specified in the ENGINE clause of a CREATE TABLE statement, it indicates that the table will be created using the InnoDB storage engine. InnoDB provides features such as transactions, foreign key constraints, and row-level locking, making it suitable for transactional workloads.
89
Which command is used for showing current date and time in Mysql command line tool?
Discuss
Answer & Solution
Answer: Option A
Solution:
To display the current date and time in MySQL command line tool, the correct command is to use the SELECT statement with the NOW() function.

Let's analyze each option:
Option A: select now(): This option is correct. By using the SELECT statement followed by the NOW() function, you can retrieve the current date and time in MySQL.
Option B: SELECT time(): This option is incorrect. The TIME() function is used to extract the time part from a datetime expression, but it doesn't display the current date and time on its own.
Option C: SELECT currenttime(): This option is incorrect. There is no function named CURRENTTIME() in MySQL. The correct function to use for the current date and time is NOW().
Option D: None of the mentioned: This option is incorrect as there is a suitable command available to display the current date and time in MySQL command line tool.

Therefore, the correct answer is Option A: select now(), as it accurately represents the command used to show the current date and time in MySQL command line tool.
90
Which datatype means a variable length non binary string?
Discuss
Answer & Solution
Answer: Option A
Solution:
In MySQL, the datatype that represents a variable-length non-binary string is VARCHAR.

Let's analyze each option:
Option A: VARCHAR: This is the correct answer. VARCHAR stands for "variable character". It is used to store variable-length non-binary strings.
Option B: BINARY: This option is incorrect. BINARY is used to store fixed-length binary strings.
Option C: VARBINARY: This option is incorrect. VARBINARY is used to store variable-length binary strings.
Option D: BLOB: This option is incorrect. BLOB stands for "Binary Large Object" and is used to store large binary data.

Therefore, the correct answer is Option A: VARCHAR, as it represents the datatype for a variable-length non-binary string in MySQL.