Unlocking the Power of FULL OUTER JOIN in SQL: Performance, Use Cases & Examples
Discover how the FULL OUTER JOIN in SQL can simplify queries, improve performance, and solve real-world data problems
2025-11-10
Outer Joins
Unlocking the Power of FULL OUTER JOIN in SQL: Performance, Use Cases & Examples
The JOIN statement is one of the most common operations SQL developers perform. Yet in a world ruled by Inner and Left Joins, the poor Full Outer Join is like Cinderella before the ball – allowed out on only the rarest of occasions. In an (unscientific) survey I once performed of SQL developers at one Fortune 100 firm, half of the developers had never used a Full Outer Join in production code, and the rest had used it in a tiny handful of occasions.
2025-10-01
2019-12-12
958 reads
Understanding Outer Joins in SQL
The basics of outer joins are shown in this short piece that explains how they work.
2019-11-19
9,651 reads
2015-12-17
1,700 reads
Outer Join – What am I missing (SQL Spackle)
This article shows how to find missing rows in a table using a outer join.
2024-10-18 (first published: 2013-11-12)
24,276 reads
2012-12-27
2,099 reads
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Fun with JSON II
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Changing Data Types
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Answering Questions On Dropped Columns
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Question of the Day
Fun with JSON II
I have some data in a table:
CREATE TABLE #test_data
(
id INT PRIMARY KEY,
name VARCHAR(100),
birth_date DATE
);
-- Step 2: Insert rows
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT t1.[key] AS row,
t2.*
FROM OPENJSON(
(
SELECT t.* FROM #test_data AS t FOR JSON PATH
)
) t1
CROSS APPLY OPENJSON(t1.value) t2; See possible answers