Database Concepts and SQL Quiz

What is a primary key in a database?

• A type of foreign key

• A method of data validation

• A type of data type

• A unique identifier for a record in a table

Which SQL statement is used to retrieve data from a database?

• INSERT

• SELECT

• UPDATE

• DELETE

What does the WHERE clause do in an SQL query?

• Sorts the results

• Joins tables

• Filters records based on a condition

• Groups records

What is the purpose of data validation?

• To ensure data integrity

• To create tables

• To delete records

• To sort data

Which of the following is a data type check?

• Ensuring age is between 0 and 120

• Verifying a name is less than 50 characters

• Ensuring a number is entered in a numeric field

• Checking if a field is not blank

What does the DISTINCT keyword do in SQL?

• Returns all records

• Filters records

• Returns unique values

• Sorts records

Which SQL command is used to add new rows to a table?

• DELETE

• INSERT

• UPDATE

• SELECT

What is an INNER JOIN?

• Returns rows only when there's a match in both tables

• Returns all records from both tables

• Returns all rows from the right table

• Returns all rows from the left table

What does the COUNT() function do in SQL?

• Calculates the average of values

• Counts the number of rows

• Finds the maximum value

• Returns the sum of values

Which of the following is a valid SQL command to delete records?

• DELETE FROM table_name WHERE condition;

• REMOVE FROM table_name;

• DELETE table_name;

• DROP table_name;