SQL Interview Questions : How to Handle Null Values in Joins (Inner, Left, Right, Full outer)
Welcome to TheTechTown In this video, we’ll dive deep into one of the most frequently asked SQL interview topics: JOINS. You’ll learn how to use Inner join, Left join, Right join, and FUull outer join to retrieve data, and I’ll also show you how to extract only NULL values in JOIN operations, a crucial technique for SQL interviews and real-world scenarios.
create table t1 (id int);
create table t2 (id int);
insert into t1 values (1),(1),(1),(2),(3),(3),(3),(null),(null);
insert into t2 values (1),(1),(2),(2),(4),(null);
By the end of this video, you will have a clear understanding of how these JOINs work, how to apply them effectively, and how to answer tricky interview questions confidently. Perfect for SQL beginners and advanced users preparing for interviews.
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Topics Covered:
What are JOINS in SQL?
INNER JOIN: Combining matching rows from two tables.
LEFT JOIN: Returning all rows from the left table and matching rows from the right.
RIGHT JOIN: Opposite of LEFT JOIN.
FULL OUTER JOIN: Returning all rows when there is a match in either table.
How to find only NULL values using JOINs.
Real interview scenarios explained.
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