MySQL mcq questions and answers | MySQL MCQs

This question asks about how to get rid of repeated rows in a table's results.
Imagine you have a list of fruits, and some fruits appear multiple times.
You want to see only one of each fruit, not all the repetitions.
That's what the DISTINCT keyword does.
So the answer is Option C: DISTINCT.
Option A: DISTINCTS is incorrect because it is not a valid keyword.
Option B: MODIFY is used to change the structure of a table, not to remove duplicates.
Option D: All of the mentioned is incorrect because only DISTINCT is the correct keyword.

This question is about using the LIKE operator in MySQL to filter data based on patterns in a column. Here's a breakdown of the code and the options:
The Code
```sql SELECT * FROM employee WHERE lname LIKE ‘_a%e%’; ```
* SELECT *: This tells MySQL to retrieve all columns (fields) from the table. * FROM employee: This specifies the table named "employee" to pull data from. * WHERE lname LIKE ‘_a%e%’: This is the filtering condition. Let's understand the pattern: * _a: This means the second letter in the last name must be "a". * %: This is a wildcard character representing any number of characters (zero or more). * e%: This means there must be at least one "e" somewhere after the second letter.
The Options
* Option A: This is partially correct. It correctly identifies that the second letter must be "a". However, it doesn't include the requirement for at least one "e" in the name. * Option B: This is incorrect. While the code does include an "e", it doesn't specify that the "e" must be anywhere in the name. The code is more specific. * Option C: This is correct. This option accurately reflects the pattern used in the LIKE clause: the second letter must be "a", and there has to be at least one "e" in the name. * Option D: This is incorrect. Only Option C is entirely accurate, and the other options are partially or fully wrong.
Therefore, the correct answer is Option C.

This question is asking about a tool used to keep MyISAM tables in good shape. Think of it like a tool to fix a broken toy!

MyISAM is an older type of table storage in MySQL. It's like a specific way to organize data.

Out of the options, myisamchk is the tool designed for fixing and checking MyISAM tables.

So the answer is Option C: myisamchk.

This question asks whether the MySQL server can be configured.
Think about it like this: If you have a car, you can change things like the speed limit, the music playing, and even the color!
Similarly, a MySQL server lets you customize things like:
* How much data it stores
* How fast it runs
* What users can access it
So, the answer is False. You can configure a MySQL server!

This MySQL command is asking the database to select specific information from the 'employee' table. Let's break down what each part does:
`SELECT emp_id,` This tells the database to retrieve the values from the column named 'emp_id'.
`‘ACTIVE’ AS STATUS,` This creates a new column named 'STATUS' and assigns the value 'ACTIVE' to all rows. In simpler terms, it's adding a column that will always show "ACTIVE."
`emp_id * 3.14 AS emp_pi,` This creates a new column named 'emp_pi' and multiplies the value of 'emp_id' by 3.14 (which is approximately pi) for each row.
`UPPER (lname) AS last_name` This creates a new column named 'last_name' and converts the values in the 'lname' column to uppercase letters.
`FROM employee;` This tells the database to retrieve data from the 'employee' table.
So, what will be the result? The command will create a new table with the following columns:
* emp_id - The original values from the 'emp_id' column.
* STATUS - All values will be 'ACTIVE'.
* emp_pi - The 'emp_id' values multiplied by 3.14.
* last_name - The 'lname' values in uppercase.
Therefore, the correct answer is Option B: emp_id, Status, emp_pi, last_name

This question is asking you to identify what "abc" represents in a MySQL DELETE statement.
The statement you see is used to remove data from a database table. Let's break it down:
`DELETE FROM xyz`: This part tells MySQL to delete rows from the table named "xyz".
`WHERE abc = 5`: This part specifies which rows to delete. It says to delete only the rows where the column named "abc" has the value 5.
Therefore, "abc" is the column name in this statement.
So the correct answer is Option A: column name.

This question is about how we change the structure of our tables in MySQL.
Imagine your table is like a spreadsheet with columns and rows.
"MODIFY" is a command that lets us change the existing columns in our table.

Out of the given options, "ALTER" is the query clause that works with "MODIFY."

So the answer is Option A: ALTER.

Think of it like this:

ALTER TABLE (This tells MySQL we want to change a table)
MODIFY (This tells MySQL we want to change a column within that table)

For example, if you want to change the data type of a column from 'INT' to 'VARCHAR', you would use the "ALTER" clause with "MODIFY".

This question asks about a special symbol used in MySQL that can have different meanings depending on what you're doing.

Think of it like a box that can hold different things. The symbol is like the box, but the specific thing inside the box changes.

The answer is $sth.

$sth is often used to represent a prepared statement, which is a way to write a SQL query once and then use it with different values. This is useful when you have a lot of similar queries.

Let's look at why the other options are incorrect:

* $dbh is usually used to represent a database handle, which connects your program to the MySQL server.
* $fh is often used for file handles, which are used to work with files on your computer.
* $h is not a common symbol in MySQL.

So, $sth is the generic handle that can mean different things depending on the context.

This question asks about the type of table "person_1" is in a MySQL query. Let's break it down:

The code you see is a CREATE VIEW statement. Views in MySQL are like special virtual tables.

Here's why:
* They don't store data directly: A view doesn't have its own data. It simply takes data from another table (in this case, the "person" table). * They act as a shortcut: Views let you select specific columns (fname, lname, person_id) from the "person" table and give them a new name ("person_1"). This makes accessing the data easier.

So, the answer is Option B: Virtual Tables.