Selection operation implementation in DBMS Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the SQL query to select all columns from the table named 'employees'.

DBMS Theory

SELECT [1] FROM employees;

Drag options to blanks, or click blank then click option'

A*

BALL

CEMPLOYEES

DCOLUMNS

Attempts:

3 left

💡 Hint

Common Mistakes

Using the table name instead of * to select all columns.

Using keywords like ALL or COLUMNS which are not valid in this context.

The asterisk (*) symbol in SQL means to select all columns from the specified table.

2fill in blank

medium

Complete the SQL query to select only the 'name' column from the 'employees' table.

DBMS Theory

SELECT [1] FROM employees;

Drag options to blanks, or click blank then click option'

Aage

Bsalary

Cname

Ddepartment

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting a column that does not exist or is unrelated.

Using * instead of a specific column name.

To select a specific column, write its exact name after SELECT.

3fill in blank

hard

Fix the error in the SQL query to select employees with salary greater than 50000.

DBMS Theory

SELECT * FROM employees WHERE salary [1] 50000;

Drag options to blanks, or click blank then click option'

A>

B=

C<

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' which means equal, not greater than.

Using '<' or '<=' which mean less than.

The operator '>' means greater than, which matches the requirement.

4fill in blank

hard

Fill both blanks to select employees whose age is between 25 and 40.

DBMS Theory

SELECT * FROM employees WHERE age [1] 25 AND age [2] 40;

Drag options to blanks, or click blank then click option'

A>=

B<

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using > or < which exclude boundary values.

Mixing up the order of operators.

To select ages between 25 and 40 inclusive, use >= 25 and <= 40.

5fill in blank

hard

Fill all three blanks to select employee names and salaries where salary is above 60000 and department is 'Sales'.

DBMS Theory

SELECT [1], [2] FROM employees WHERE salary [3] 60000 AND department = 'Sales';

Drag options to blanks, or click blank then click option'

Aname

Bsalary

C>

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting wrong columns like 'age' instead of 'salary'.

Using '=' instead of '>' for salary condition.

Select the columns 'name' and 'salary', and use '>' to filter salaries above 60000.