MySQL mcq questions and answers | MySQL MCQs

This question is about the CHECK TABLE command in MySQL and which storage engines it works with.

CHECK TABLE is a command that checks the consistency of a table, making sure all the data is in order and there are no errors.

Now, we have to figure out which storage engines work with CHECK TABLE. Storage engines are like different ways MySQL manages data in tables.

The options provided are:
* MyISAM: A commonly used storage engine for MySQL.
* ARCHIVE: A storage engine for storing data in a compressed form, mainly for read-only tables.
* CSV: A storage engine that treats tables as CSV files.

The correct answer is Option B: 1. Only MyISAM storage engine supports CHECK TABLE.

ARCHIVE and CSV storage engines don't have the functionality to perform table checks. They are designed differently and prioritize other features.

This question asks about a type of join in SQL. A join combines data from two tables based on a common column. Let's understand the different join types:

Option A: CARTESIAN JOIN
This type of join creates a new table containing all possible combinations of rows from both tables. It's not commonly used, as it can result in a huge dataset.

Option B: CROSS JOIN
This join is similar to a CARTESIAN JOIN. It also creates a new table with all possible combinations of rows from both tables. This is the same as a CARTESIAN JOIN.

Option C: INNER JOIN
This join returns rows only when there's a match in the common column of both tables. It only keeps rows with matching values.

Option D: RIGHT JOIN
This join returns all the rows from the table on the right side of the JOIN clause. It also includes rows from the left table where there's a match in the common column. If no match exists, it shows NULL values for columns from the left table.

Therefore, the answer is Option D: RIGHT JOIN as it guarantees that all rows from the right table will appear in the output, even if there's no matching value in the left table.

This question is asking about a database that is automatically created when you install MySQL on your computer. This database is essential for managing and accessing information about your MySQL server.

Let's look at the options:

Option A: sampdb - This is not a standard database in MySQL.
Option B: mysql - This is the correct answer! The mysql database is a special database that is always created when you set up MySQL. It stores information about users, permissions, and other important configuration settings.
Option C: information_schema - This database is also important, but it's not automatically created during installation. It's a special database that contains information about the structure of your other databases and tables.
Option D: readme_db - This is not a real database in MySQL.

Therefore, the answer is Option B: mysql.

This question asks about the name given to information that describes the structure and details of databases and the objects they contain in MySQL.

Let's break down the options:

Option A: datum - A datum refers to a single piece of information. It's too specific for describing the overall information about a database.

Option B: info - While general, "info" doesn't specifically refer to the structured description of databases and objects.

Option C: record - A record is a collection of data related to a single entity within a database. It's not the term for describing the database structure itself.

Option D: metadata - This is the correct answer! Metadata refers to information about data. In the context of MySQL, it describes the database structure, table definitions, column types, relationships, and other details.

Think of metadata like a blueprint for your database. It helps you understand how the database is organized and what kind of data it stores.

This question asks if MySQL allows you to run multiple SQL statements at once by default.
Think of it like giving a set of instructions to a computer.
In MySQL, you can write several instructions, one after another, and they will be executed in order.
So the answer is True.
By default, MySQL allows you to execute multiple statements together.
You don't have to turn on any special settings to do this.
This makes it easy to perform multiple tasks with a single query.
For example, you could create a new table, insert data into it, and then select data from it, all within a single query.

This question asks about the DIV operator in MySQL.
DIV is used for integer division, meaning it only gives you the whole number result, ignoring any remainder.

In this case, 12 divided by 5 equals 2.4.
However, DIV only gives the whole number part, which is 2.

So the correct answer is Option B: 2.

This question asks about the speed of calculations in MySQL.
MySQL is a database system that can store and manipulate data, including numbers and strings.

Let's break down the options:

Option A: True
This means calculations with numbers are faster than calculations with strings.

Option B: False
This means calculations with strings are just as fast as calculations with numbers, or even faster.

To answer the question, we need to think about how MySQL handles different data types.
MySQL is optimized for numerical calculations.
When you perform calculations with numbers, MySQL can directly use mathematical operations, making them very efficient.

However, when you work with strings, MySQL often needs to convert them to numbers first, which can add an extra step and slow down the process.

Therefore, the correct answer is Option A: True.
Calculations involving numbers are generally faster than those involving strings in MySQL.

It's important to remember that this is a general rule, and specific scenarios may vary.
But for most cases, numerical calculations will be faster in MySQL.

This question asks about a way to combine results from different SELECT statements in MySQL. Think of it like putting together pieces of a puzzle. You're trying to get a complete picture from multiple smaller pictures.

Here's how the options break down:

Option A: COMBINE - This isn't a valid keyword for combining queries in MySQL.

Option B: CONCAT - This keyword is used to join strings together, not entire query results.

Option C: JOIN - This keyword is used to combine data from different tables based on a shared column. It's not for combining separate SELECT statements.

Option D: UNION - This is the correct answer! UNION lets you combine the results of multiple SELECT statements into a single result set. Imagine you have two lists of items, and you want to create a new list that contains all the items from both lists, without duplicates.

So, to combine multiple retrievals in MySQL, you would write several SELECT statements and use the keyword UNION between them.

This question asks you about how MySQL handles data in a table and how sorting works. Here's the breakdown:

1. The Table and Data
Imagine a table called "person" that stores information about people. One column in this table is called "fruit".
The "fruit" column for a person with "person_id" equal to 1 contains the following data: "apple, mango, banana".

2. The SQL Query
The SQL query you see is designed to fetch the data in the "fruit" column. Let's break it down:
* SELECT fruit FROM person: This part tells the database to get the values from the "fruit" column in the "person" table.
* WHERE person_id=1: This part specifies that we only want the data for the person with "person_id" equal to 1.
* ORDER BY fruit: This part tells MySQL to arrange the result alphabetically based on the "fruit" values.

3. Understanding the Output
Since "fruit" is stored as "apple, mango, banana", the "ORDER BY fruit" clause will sort these values alphabetically. Therefore, the output will be:
apple, banana, mango

The Correct Answer:
Option B: apple, banana, mango is the correct answer.