MySQL mcq questions and answers | MySQL MCQs

The "ORDER BY" clause in a MySQL statement is like telling the database to arrange the results in a specific order.
In this case, "ORDER BY emp_id" means the results will be sorted based on the values in the "emp_id" column.
By default, the sorting is done in ascending order, meaning the lowest values of "emp_id" will appear first.
So the answer is Option C: Data of emp_id will be sorted in ascending order.

This question asks about REPAIR TABLE in MySQL and its relation to upgrading your MySQL version.
REPAIR TABLE is used to fix errors in your database tables.
The USE_FRM option tells MySQL to use the table's .frm file (which contains the table structure) to help with the repair.
The answer:
While it's good practice to repair tables before upgrading, it's not mandatory.
So the answer is Option B: False.
You can upgrade even if you haven't used REPAIR TABLE with USE_FRM.
However, running REPAIR TABLE can help ensure your tables are in good shape before upgrading.

This MySQL command is designed to update information in a table named "person".
Let's break down the command:
UPDATE person : This part tells MySQL to modify data in the "person" table.
SET lname='s', Fname='p' : This part specifies the changes to be made. It sets the "lname" (last name) column to 's' and the "Fname" (first name) column to 'p'.
WHERE person_id=1 : This is crucial! It restricts the update to only the row where "person_id" equals 1.
Since "person_id" is a primary key, it uniquely identifies each row in the table. This means only one row can have "person_id=1".
Therefore, the correct answer is Option A: Single row.
The command will update only the row with the primary key "person_id" equal to 1.

This question is asking about operators in MySQL that compare values. Let's break down the options:
Option A: = This operator checks if two values are equal. It compares the values relatively.
Option B: == This operator also checks if two values are equal. It's the same as using "=", so it performs relative comparisons.
Option C: <= This operator checks if a value is less than or equal to another value. It performs relative comparisons by comparing the values based on their order.
Option D: >= This operator checks if a value is greater than or equal to another value. It performs relative comparisons similar to option C.
Therefore, none of the operators (A, B, C, or D) perform absolute comparisons. They all compare values relatively based on their size or order.

This question is about the order of including header files in MySQL. Header files provide definitions and declarations that are needed by the MySQL code.
Here's the breakdown:
Option A: my_global.h - This header file contains global definitions and configurations for MySQL. It needs to be included first as it defines crucial settings for the entire system.
Option B: my_sys.h - This header file handles system-related definitions, which are also important. It usually needs to be included after my_global.h.
Option C: mysql.h - This header file includes specific definitions related to the MySQL API (Application Programming Interface). It's included after both my_global.h and my_sys.h.
Option D: my_local.h - This header file contains local definitions, which are often specific to a particular module or component of MySQL. It's usually included after mysql.h.
Therefore, the correct answer is Option A: my_global.h

This question asks about how you declare a column that can hold a varying amount of text in an Oracle database. Let's break down the options:
Option A: Varchar
This is a common data type for storing variable-length strings in many databases, including MySQL.
Option B: Varchar 3
This looks like a specific example of using VARCHAR, but it's incomplete. The "3" would typically represent the maximum length of the string.
Option C: Varchar2
This is the correct answer! In Oracle, Varchar2 is used for storing variable-length character strings.
Option D: None of the mentioned
Since Varchar2 is a valid data type for variable-length strings in Oracle, this option is incorrect.
In short, you would use Varchar2 to declare a column that can hold text of varying lengths in an Oracle database.

In a database, a transaction is a sequence of operations that are treated as a single unit. Imagine you're transferring money from one account to another. This whole process, from checking your balance to confirming the transfer, is considered a transaction.
Now, the isolation property ensures that multiple transactions happening at the same time don't interfere with each other.
Think of it like this: You're at the bank, and someone else is doing a transaction at the same time. The isolation property makes sure that your transaction doesn't get mixed up with theirs, and your money ends up in the right place.
So, the correct answer is Option C: one transaction does not affect the other.
Let's look at why the other options are incorrect:
Option A: statements form a logic unit - This describes the atomicity property of transactions, meaning all operations within a transaction happen or none of them do.
Option B: database remains consistent - This describes the durability property, ensuring changes made by a successful transaction are permanently stored.
Option D: transaction effects are recorded permanently - This again relates to the durability property.
Therefore, the isolation property specifically focuses on preventing conflicts between concurrent transactions.

This question asks about a function in MySQL that provides information about errors that occur during database operations.
Let's understand the options:
Option A: mysql_error()
This function returns a string containing the actual error message.
Option B: mysql_errno()
This function returns an integer representing the error number.
Option C: mysql_sqlstate()
This function returns a five-character SQLSTATE error code.
Option D: mysql_close()
This function closes a database connection and doesn't return an error message.
Therefore, the correct answer is Option A: mysql_error() because it specifically returns the error message as a string.

This question is asking about which function in MySQL gives you a number that specifically tells you what kind of error happened. Let's break down the options:
Option A: mysql_error() * This function gives you a text description of the error that occurred. It's useful for understanding what went wrong, but it doesn't give you a specific number.
Option B: mysql_errno() * This is the correct answer! This function gives you a numeric code that represents the specific error that occurred. This code can be helpful for troubleshooting and identifying the problem.
Option C: mysql_sqlstate() * This function gives you a SQLSTATE code, which is a standard error code used in SQL databases. It's not specific to MySQL.
Option D: mysql_close() * This function is used to close a MySQL connection and doesn't return an error code.
In summary, the function that returns a MySQL-specific numeric code is mysql_errno().