MySQL mcq questions and answers | MySQL MCQs

This question is asking about how to find out what character set and collation your MySQL server is using. These settings determine how text is stored and compared in your database. Here's a breakdown of the options: * Option A: SHOW CONSTANTS - This command shows various constants defined within MySQL. It's not directly related to character sets and collations. * Option B: SHOW CONSTRAINTS - This command shows the constraints defined on tables in your database. It's not related to server settings. * Option C: SHOW VARIABLES - This is the correct answer! This command displays all system variables and their current values. This includes the character set and collation settings for the server. * Option D: DISP VARIABLES - This is a synonym for SHOW VARIABLES. Both commands do the same thing. In summary, the correct answer is Option C: SHOW VARIABLES.

This question is about how MySQL tells you how many rows were affected by an operation like inserting, updating, or deleting data.
Let's break down the options:
Option A: $rc - This is a common variable used to store the row count in many programming languages, but not in standard MySQL.
Option B: $rv - This is a variable often used for return values, but it's not specifically for row counts in MySQL.
Option C: $rows - This is a variable that might store rows, but it's not the standard way MySQL reports the number of affected rows.
Option D: $ary - This looks like a placeholder for an array and isn't related to row counts in MySQL.
The correct answer is none of the above. MySQL uses the ROW_COUNT() function to get the number of rows affected by the last statement.
For example, if you ran `DELETE FROM my_table WHERE id = 1;` and it deleted one row, then `SELECT ROW_COUNT();` would return `1`.
Key takeaway: MySQL uses `ROW_COUNT()` to find out how many rows were changed.

This question asks about how to load data from a file that has data separated by a specific character (like a comma or tab). Think of it like a spreadsheet saved as a text file.

The command used for this is mysqlimport.

Let's break down why the other options aren't correct:

* mysqlexport: This command is used to export data from a MySQL database to a file. It's the opposite of what we want to do.
* mysqlexpand: This command doesn't exist in MySQL.
* mysqltransfer: This command isn't a standard part of MySQL.

Therefore, the correct answer is Option B: mysqlimport

This question asks about the LOAD DATA command in MySQL and its LOCAL capability.

The LOCAL capability allows you to load data from a file on the server where MySQL is running, rather than from a remote server.

The question asks if you need to explicitly enable this capability.

The answer is False (Option B).

You do not need to explicitly enable the LOCAL capability. It is enabled by default in MySQL.

However, it's important to be aware of potential security implications of using LOCAL, as it could allow unauthorized access to files on the server.

This question is about how MySQL handles changes to indexes. Indexes help speed up searching in your database.

The answer is Option B: -delay-key-write.

Let's break down why:

* -delay-key-write: This option tells MySQL to delay writing changes to indexes until the table is closed. This can improve performance, especially for write-heavy operations.
* Option A & C: These options don't exist in MySQL.
* Option D: While similar in concept to -delay-key-write, it's not the correct option.

Important Note: Delaying index writes can sometimes lead to data loss if the server crashes before the changes are written. So, use it carefully!

This question tests your understanding of the BETWEEN operator in MySQL.
The BETWEEN operator is used to check if a value falls within a specified range.
The expression `2 BETWEEN 2 AND 5` checks if the value `2` is between `2` and `5`, inclusive.
Since `2` is equal to `2` and is within the specified range, the expression evaluates to True.

Therefore, the correct answer is Option A: True.

This question is asking about how you create a stored function in MySQL. A stored function is like a mini-program that you can store in your database and call whenever you need it. It's a way to make your database code more organized and reusable.

Out of the options given, the correct answer is Option B: CREATE FUNCTION.

Let's break down the other options:

* Option A: PRODUCE FUNCTION - This is not a valid MySQL command.
* Option C: PRODUCE PROCEDURE - This is also not a valid MySQL command.
* Option D: CREATE PROCEDURE - This command is used to create a stored procedure, which is similar to a function, but doesn't return a value.

So, to create a stored function, you would use the CREATE FUNCTION statement.

This question asks about how MySQL handles the logical OR operator (OR) when one of the values is NULL.
Here's how it works:
* TRUE OR TRUE: The result is TRUE.
* TRUE OR FALSE: The result is TRUE.
* FALSE OR TRUE: The result is TRUE.
* FALSE OR FALSE: The result is FALSE.
* TRUE OR NULL: The result is TRUE.
* FALSE OR NULL: The result is TRUE.
In MySQL, NULL is considered unknown in logical operations.
The OR operator returns TRUE if at least one of the values is TRUE.
Since NULL is considered "unknown" in this case, the OR operator assumes it might be TRUE.
Therefore, "TRUE OR NULL" will evaluate to TRUE.
So the answer is Option A: True