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Db2
Firebird
MariaDB
MySQL
Node.js
Oracle
Postgres
SQLite
SQL Server
TimescaleDB
YugabyteDB
Developer-C 11.1
3.0
4.0
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
5.5
5.6
5.7
8.0
18
11g Release 2
18c
21c
23c
8.4
9.3
9.4
9.5
9.6
10
11
12
13
14
15
16
3.8
3.16
3.27
3.39
2012
2014
2016
2017
2017 (Linux)
2019
2019 (Linux)
2022
2.11
2.6
2.8
2.18
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Sakila
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AdventureWorks
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AdventureWorks
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DECLARE @A table (A integer NULL, B integer NULL); DECLARE @B table (A integer NULL, B integer NULL); INSERT @A (A, B) VALUES (1, 1); INSERT @B (A, B) VALUES (2, 2); -- Original APPLY SELECT * FROM @A AS A CROSS APPLY (SELECT c = COUNT_BIG(*) FROM @B AS B WHERE B.A = A.A) AS CA; -- Correctly rewritten as a JOIN SELECT A.*, c = COALESCE(J1.c, 0) FROM @A AS A LEFT JOIN ( SELECT B.A, c = COUNT_BIG(*) FROM @B AS B GROUP BY B.A ) AS J1 ON J1.A = A.A; -- Incorrect result wthout the COALESCE SELECT A.*, J1.c FROM @A AS A LEFT JOIN ( SELECT B.A, c = COUNT_BIG(*) FROM @B AS B GROUP BY B.A ) AS J1 ON J1.A = A.A; -- Incorrect result with INNER JOIN SELECT A.*, J1.c FROM @A AS A INNER JOIN ( SELECT B.A, c = COUNT_BIG(*) FROM @B AS B GROUP BY B.A ) AS J1 ON J1.A = A.A;
A
B
c
1
1
0
A
B
c
1
1
0
A
B
c
1
1
null
A
B
c