SQL Joins Quiz: Test Your Knowledge with SQL Join Queries

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Questions and Answers

What is the purpose of the INNER JOIN clause in SQL?

To return all rows from the left table and the matching rows from the right table.

To count the number of rows in a table that match a specific condition.

To return all rows from the right table and the matching rows from the left table.

To combine all rows from both tables where the condition is satisfied, i.e., the values of the common field are the same. (correct)

What is the purpose of the LEFT JOIN clause in SQL?

To return all rows from the right table and the matching rows from the left table.

To combine all rows from both tables where the condition is satisfied, i.e., the values of the common field are the same.

To return all rows from the left table and the matching rows from the right table. (correct)

To calculate the average value of a column in a table.

What is the purpose of the RIGHT JOIN clause in SQL?

To calculate the sum of values in a column in a table.

To combine all rows from both tables where the condition is satisfied, i.e., the values of the common field are the same.

To return all rows from the right table and the matching rows from the left table. (correct)

To return all rows from the left table and the matching rows from the right table.

Which SQL function is used to calculate the average value of a column in a table?

AVG() Signup and view all the answers

Which SQL function is used to count the number of rows in a table that match a specific condition?

COUNT() Signup and view all the answers

What does an SQL INNER JOIN return?

All records with matching values in both tables Signup and view all the answers

Which type of SQL join returns all records from the left table and matched records from the right?

Left join Signup and view all the answers

In SQL, what does a RIGHT JOIN return?

All records from the right table and matched records from the left Signup and view all the answers

When using a FULL JOIN in SQL, what does it return?

All records from both tables regardless of match Signup and view all the answers

Which SQL join type would be suitable if you want to return all rows with matching values in both tables?

INNER JOIN Signup and view all the answers

In an SQL LEFT JOIN, what happens to rows that don't have a match in the right table?

They are included with NULL values for columns of the right table Signup and view all the answers

What is a key benefit of using SQL join statements in database queries?

Reducing data anomalies during record deletion or update Signup and view all the answers

Which SQL join type returns all records when there is a match in either the left or right table?

(FULL) JOIN Signup and view all the answers

What does a CROSS JOIN in SQL do?

Returns all possible combinations between the two tables Signup and view all the answers

Study Notes

SQL Server

SQL Server is a relational database management system (RDBMS) that allows users to access and manipulate data in a database.

SQL JOINS

SQL join statements allow us to access information from two or more tables at once.
They also keep our database normalized, which helps to keep data redundancy low and decrease the amount of data anomalies in our application when we delete or update a record.

Types of JOINS

INNER JOIN: Returns dataset that have matching values in both tables.
LEFT (OUTER) JOIN: Returns all records from the left table and matched records from the right.
RIGHT (OUTER) JOIN: Returns all records from the right table and the matched records from the left.
FULL (OUTER) JOIN: Returns all records when there is a match in either the left table or right table.

SQL INNER JOINS

The INNER JOIN keyword selects all rows from both the tables as long as the condition satisfies.
Syntax: SELECT column_name(s) FROM table1 INNER JOIN table2 ON table1.column_name = table2.column_name;
Example: SELECT StudentCourse.COURSE_ID, Student.naw, Student.taman FROM Student INNER JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO;

SQL LEFT JOINS

This join returns all the rows of the table on the left side of the join and matching rows for the table on the right side of join.
The rows for which there is no matching row on right side, the result-set will contain null.
Syntax: SELECT column_name(s) FROM table1 LEFT JOIN table2 ON table1.column_name = table2.column_name;
Example: SELECT StudentCourse.COURSE_ID, Student.naw, Student.taman FROM Student LEFT JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO;

SQL RIGHT JOINS

This join returns all the rows of the table on the right side of the join and matching rows for the table on the left side of join.
The rows for which there is no matching row on left side, the result-set will contain null.
Syntax: SELECT column_name(s) FROM table1 RIGHT JOIN table2 ON table1.column_name = table2.column_name;
Example: SELECT StudentCourse.COURSE_ID, Student.naw, Student.taman FROM Student RIGHT JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO;

SQL FULL JOINS

This join creates the result-set by combining result of both LEFT JOIN and RIGHT JOIN.
The result-set will contain all the rows from both the tables.
The rows for which there is no matching, the result-set will contain NULL values.
Syntax: SELECT column_name(s) FROM table1 FULL JOIN table2 ON table1.column_name = table2.column_name;
Example: SELECT StudentCourse.COURSE_ID, Student.naw, Student.taman FROM Student FULL JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO;

SQL CROSS JOINS

This join is a join of tables without specifying the join condition.
In this scenario, the query would return all possible combination of the tables in the SQL query.
Syntax: SELECT column1, column2,….FROM table1 CROSS JOIN table2;
Example: SELECT naw, taman FROM tbl_student CROSS JOIN student_course;

SQL SELECT Statements

SELECT with SUM(): Write SQL statement to Select with SUM().
SELECT TOP syntax: Write SELECT TOP syntax.
Select with HAVING syntax: Write Select with having syntax.

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Description

Test your knowledge of SQL joins and select statements with this quiz. Learn about different types of joins like inner joins, left joins, right joins, full joins, and cross joins. Understand how to use SUM() in SELECT statements and the syntax for SELECT TOP and SELECT with HAVING.