Mastering SQL Basics

What does SQL stand for?

• Structured Query Language

• Structured Query List

• Standard Query Language

• Simple Query Language

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

• DELETE

• UPDATE

• SELECT

• INSERT

How do you insert new data into a table in SQL?

• DELETE FROM table_name WHERE column1 = value1;

• UPDATE table_name SET column1 = value1;

• INSERT INTO table_name (column1, column2) VALUES (value1, value2);

• SELECT * FROM table_name WHERE column1 = value1;

What is the purpose of the WHERE clause in SQL?

• To create new records in the database.

• To filter records based on specified conditions.

• To join multiple tables together.

• To sort records in ascending order.

Which SQL command is used to update existing data?

• INSERT

• DELETE

• UPDATE

• SELECT

What is a primary key in a database?

• A primary key is a type of foreign key.

• A primary key can be duplicated across records.

• A primary key is a unique identifier for a record in a database.

• A primary key is an optional field in a database.

How do you delete data from a table in SQL?

• DELETE FROM table_name WHERE condition;

• DROP table_name WHERE condition;

• REMOVE FROM table_name WHERE condition;

• DELETE table_name FROM WHERE condition;

What is the difference between INNER JOIN and LEFT JOIN?

• INNER JOIN returns matched rows; LEFT JOIN returns all left rows with matched right rows or NULLs.

• INNER JOIN includes NULL values from the left table.

• LEFT JOIN only returns rows from the right table.

• INNER JOIN returns all rows from both tables.

What SQL function is used to count the number of rows in a table?

• SUM()

• AVG()

• MAX()

• COUNT()

What is a foreign key in SQL?

• A foreign key is a field that can only contain null values.

• A foreign key is a field in one table that links to the primary key of another table.

• A foreign key is a type of index used for faster queries.

• A foreign key is a unique identifier for a table.