MySQL 来自相同表的 3 行，它们相互匹配
MySQL 3 rows from the same tables WHERE they match eachother
编辑 - 回应@Strawberry
在@Strawberry 的推荐下，我阅读了有关规范化的内容，它震撼了我的整个布局。下面是我的新布局的模型。它将大大减少长 运行 中的 table 大小。如果你们有任何疑虑，请告诉我到目前为止的任何疑虑。
布局完成后，我将编辑我的脚本并 运行 向其中输入一些数据。然后尝试沿着不同的路径找出相同的问题。
任何指点总是好的。谢谢@Strawberry 的建议。
我正在开发数独及其变体的数据库。我的问题在于变体。这些变体由 2 个或更多重叠的拼图组成，用于我想出的 2 个拼图。
我用来构建 Samurai x2 谜题列表的 Powershell 脚本
$samurai2 = "SELECT region9.ID, region1.ID FROM region9, region1 WHERE region9.Puz = region1.Puz AND region9.Ans = region1.Ans AND NOT EXISTS ( SELECT 1 FROM samurai2 AS c WHERE c.Puz1 = region9.ID AND c.Puz2 = region1.ID);"
Invoke-MySqlQuery -Query $samurai2 | ForEach {
$found = "SELECT * FROM sudoku.sudoku9x9 WHERE ID = $($_.'ID') OR ID = $($_.'ID1')"
$found = (Invoke-MySqlQuery -Query $found)
$diff = ([int]$found.'diff'[0] + [int]$found.'diff'[1]) / 2
$samurai = "INSERT INTO ``samurai2``(``Diff``, ``Puz1``, ``Puz2``) VALUES ('$diff', '$($_.'ID')', '$($_.'ID1')')"
Invoke-MySqlQuery -Query $samurai
}
我一直在想办法找出 3 个或更多重叠的谜题。
武士 x3
Puz1 区域 9 = Puz2 区域 1
Puz2 区域 9 = Puz3 区域 1
我不知道如何区分 Puz1 Region9 & Ruz2 Region9 和 Puz2 Region1 & Puz3 Region1
数独9x9
+---------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+----------------+
| ID | int(22) | NO | PRI | NULL | auto_increment |
| StringP | varchar(81) | NO | UNI | NULL | |
| StringA | varchar(81) | NO | | NULL | |
| Diff | int(6) | NO | | NULL | |
| A1P | int(1) | YES | | NULL | |
| A2P | int(1) | YES | | NULL | |
| A3P | int(1) | YES | | NULL | |
| A4P | int(1) | YES | | NULL | |
| A5P | int(1) | YES | | NULL | |
-----------------------------------------------------------------
| I5A | int(1) | NO | | NULL | |
| I6A | int(1) | NO | | NULL | |
| I7A | int(1) | NO | | NULL | |
| I8A | int(1) | NO | | NULL | |
| I9A | int(1) | NO | | NULL | |
+---------+-------------+------+-----+---------+----------------+
区域 1 和区域 9
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| ID | int(11) | NO | PRI | NULL | |
| Puz | varchar(81) | NO | MUL | NULL | |
| Ans | varchar(81) | NO | | NULL | |
+-------+-------------+------+-----+---------+-------+
武士3
+-------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+----------------+
| ID | int(11) | NO | PRI | NULL | auto_increment |
| Diff | int(6) | YES | | NULL | |
| Puz1 | int(11) | YES | | NULL | |
| Puz2 | int(11) | YES | | NULL | |
| Puz3 | int(11) | YES | | NULL | |
+-------+---------+------+-----+---------+----------------+
编辑 - 回应@Gurwinder Singh
数独 9x9
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| ID | StringP | StringA | Diff | A1P | A2P | A3P | A4P | A5P | A6P | A7P | A8P | A9P | B1P | B2P | B3P | B4P | B5P | B6P | B7P | B8P | B9P | C1P | C2P | C3P | C4P | C5P | C6P | C7P | C8P | C9P | D1P | D2P | D3P | D4P | D5P | D6P | D7P | D8P | D9P | E1P | E2P | E3P | E4P | E5P | E6P | E7P | E8P | E9P | F1P | F2P | F3P | F4P | F5P | F6P | F7P | F8P | F9P | G1P | G2P | G3P | G4P | G5P | G6P | G7P | G8P | G9P | H1P | H2P | H3P | H4P | H5P | H6P | H7P | H8P | H9P | I1P | I2P | I3P | I4P | I5P | I6P | I7P | I8P | I9P | A1A | A2A | A3A | A4A | A5A | A6A | A7A | A8A | A9A | B1A | B2A | B3A | B4A | B5A | B6A | B7A | B8A | B9A | C1A | C2A | C3A | C4A | C5A | C6A | C7A | C8A | C9A | D1A | D2A | D3A | D4A | D5A | D6A | D7A | D8A | D9A | E1A | E2A | E3A | E4A | E5A | E6A | E7A | E8A | E9A | F1A | F2A | F3A | F4A | F5A | F6A | F7A | F8A | F9A | G1A | G2A | G3A | G4A | G5A | G6A | G7A | G8A | G9A | H1A | H2A | H3A | H4A | H5A | H6A | H7A | H8A | H9A | I1A | I2A | I3A | I4A | I5A | I6A | I7A | I8A | I9A |
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | 062017009701000000000000008003061000080000000000042006006023007000000000030405010 | 862317549751984263394256178423861795685739421179542836546123987217698354938475612 | 332 | NULL | 6 | 2 | NULL | 1 | 7 | NULL | NULL | 9 | 7 | NULL | 1 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 8 | NULL | NULL | 3 | NULL | 6 | 1 | NULL | NULL | NULL | NULL | 8 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 4 | 2 | NULL | NULL | 6 | NULL | NULL | 6 | NULL | 2 | 3 | NULL | NULL | 7 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 3 | NULL | 4 | NULL | 5 | NULL | 1 | NULL | 8 | 6 | 2 | 3 | 1 | 7 | 5 | 4 | 9 | 7 | 5 | 1 | 9 | 8 | 4 | 2 | 6 | 3 | 3 | 9 | 4 | 2 | 5 | 6 | 1 | 7 | 8 | 4 | 2 | 3 | 8 | 6 | 1 | 7 | 9 | 5 | 6 | 8 | 5 | 7 | 3 | 9 | 4 | 2 | 1 | 1 | 7 | 9 | 5 | 4 | 2 | 8 | 3 | 6 | 5 | 4 | 6 | 1 | 2 | 3 | 9 | 8 | 7 | 2 | 1 | 7 | 6 | 9 | 8 | 3 | 5 | 4 | 9 | 3 | 8 | 4 | 7 | 5 | 6 | 1 | 2 |
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
region1 和 region9（两者 table 相同）
+--------+-----------+-----------+
| ID | Puz | Ans |
+--------+-----------+-----------+
| 427974 | 000000000 | 123458976 |
| 169852 | 000000000 | 123459678 |
| 162359 | 000000000 | 123468957 |
| 290352 | 000000000 | 123468975 |
| 418083 | 000000000 | 123469578 |
+--------+-----------+-----------+
samurai2（samurai3多了一个专栏Puz3）
+----+------+-------+-------+
| ID | Diff | Puz1 | Puz2 |
+----+------+-------+-------+
| 1 | 338 | 28005 | 45032 |
| 2 | 261 | 35934 | 60202 |
| 3 | 358 | 49688 | 61760 |
| 4 | 299 | 21243 | 45461 |
| 5 | 360 | 39237 | 56552 |
+----+------+-------+-------+
查询 Samurai x2 拼图和输出，x3 会有第三个 ID。
SELECT region9.ID, region1.ID FROM region9, region1 WHERE region9.Puz = region1.Puz AND region9.Ans = region1.Ans AND NOT EXISTS ( SELECT 1 FROM samurai2 AS c WHERE c.Puz1 = region9.ID AND c.Puz2 = region1.ID);
+--------+--------+
| ID | ID |
+--------+--------+
| 568557 | 33176 |
| 52551 | 567499 |
| 416691 | 567885 |
| 566193 | 472617 |
| 563401 | 567324 |
+--------+--------+
sudoku9x9 中使用的 ID 与 region1 和 region9 中的 ID 相关
根据@Strawberry 的评论研究标准化后。我重做了我的整个数据库，查看我对问题的最后编辑。使用新架构，我原来的问题很容易解决。
SELECT puz1.sudoku9x9_id, puz1.difficulty, puz2.sudoku9x9_id, puz2.difficulty, puz3.sudoku9x9_id, puz3.difficulty
FROM sudoku9x9 as puz1
INNER JOIN sudoku9x9 as puz2
INNER JOIN sudoku9x9 as puz3
WHERE
puz1.clue_9 = puz2.clue_1 AND puz1.region_9 = puz2.region_1 AND
puz2.clue_9 = puz3.clue_1 AND puz2.region_9 = puz3.region_1
编辑 - 回应@Strawberry
在@Strawberry 的推荐下，我阅读了有关规范化的内容，它震撼了我的整个布局。下面是我的新布局的模型。它将大大减少长 运行 中的 table 大小。如果你们有任何疑虑，请告诉我到目前为止的任何疑虑。
布局完成后，我将编辑我的脚本并 运行 向其中输入一些数据。然后尝试沿着不同的路径找出相同的问题。
任何指点总是好的。谢谢@Strawberry 的建议。
我正在开发数独及其变体的数据库。我的问题在于变体。这些变体由 2 个或更多重叠的拼图组成，用于我想出的 2 个拼图。
我用来构建 Samurai x2 谜题列表的 Powershell 脚本
$samurai2 = "SELECT region9.ID, region1.ID FROM region9, region1 WHERE region9.Puz = region1.Puz AND region9.Ans = region1.Ans AND NOT EXISTS ( SELECT 1 FROM samurai2 AS c WHERE c.Puz1 = region9.ID AND c.Puz2 = region1.ID);"
Invoke-MySqlQuery -Query $samurai2 | ForEach {
$found = "SELECT * FROM sudoku.sudoku9x9 WHERE ID = $($_.'ID') OR ID = $($_.'ID1')"
$found = (Invoke-MySqlQuery -Query $found)
$diff = ([int]$found.'diff'[0] + [int]$found.'diff'[1]) / 2
$samurai = "INSERT INTO ``samurai2``(``Diff``, ``Puz1``, ``Puz2``) VALUES ('$diff', '$($_.'ID')', '$($_.'ID1')')"
Invoke-MySqlQuery -Query $samurai
}
我一直在想办法找出 3 个或更多重叠的谜题。
武士 x3
Puz1 区域 9 = Puz2 区域 1
Puz2 区域 9 = Puz3 区域 1
我不知道如何区分 Puz1 Region9 & Ruz2 Region9 和 Puz2 Region1 & Puz3 Region1
数独9x9
+---------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+----------------+
| ID | int(22) | NO | PRI | NULL | auto_increment |
| StringP | varchar(81) | NO | UNI | NULL | |
| StringA | varchar(81) | NO | | NULL | |
| Diff | int(6) | NO | | NULL | |
| A1P | int(1) | YES | | NULL | |
| A2P | int(1) | YES | | NULL | |
| A3P | int(1) | YES | | NULL | |
| A4P | int(1) | YES | | NULL | |
| A5P | int(1) | YES | | NULL | |
-----------------------------------------------------------------
| I5A | int(1) | NO | | NULL | |
| I6A | int(1) | NO | | NULL | |
| I7A | int(1) | NO | | NULL | |
| I8A | int(1) | NO | | NULL | |
| I9A | int(1) | NO | | NULL | |
+---------+-------------+------+-----+---------+----------------+
区域 1 和区域 9
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| ID | int(11) | NO | PRI | NULL | |
| Puz | varchar(81) | NO | MUL | NULL | |
| Ans | varchar(81) | NO | | NULL | |
+-------+-------------+------+-----+---------+-------+
武士3
+-------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+----------------+
| ID | int(11) | NO | PRI | NULL | auto_increment |
| Diff | int(6) | YES | | NULL | |
| Puz1 | int(11) | YES | | NULL | |
| Puz2 | int(11) | YES | | NULL | |
| Puz3 | int(11) | YES | | NULL | |
+-------+---------+------+-----+---------+----------------+
编辑 - 回应@Gurwinder Singh
数独 9x9
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| ID | StringP | StringA | Diff | A1P | A2P | A3P | A4P | A5P | A6P | A7P | A8P | A9P | B1P | B2P | B3P | B4P | B5P | B6P | B7P | B8P | B9P | C1P | C2P | C3P | C4P | C5P | C6P | C7P | C8P | C9P | D1P | D2P | D3P | D4P | D5P | D6P | D7P | D8P | D9P | E1P | E2P | E3P | E4P | E5P | E6P | E7P | E8P | E9P | F1P | F2P | F3P | F4P | F5P | F6P | F7P | F8P | F9P | G1P | G2P | G3P | G4P | G5P | G6P | G7P | G8P | G9P | H1P | H2P | H3P | H4P | H5P | H6P | H7P | H8P | H9P | I1P | I2P | I3P | I4P | I5P | I6P | I7P | I8P | I9P | A1A | A2A | A3A | A4A | A5A | A6A | A7A | A8A | A9A | B1A | B2A | B3A | B4A | B5A | B6A | B7A | B8A | B9A | C1A | C2A | C3A | C4A | C5A | C6A | C7A | C8A | C9A | D1A | D2A | D3A | D4A | D5A | D6A | D7A | D8A | D9A | E1A | E2A | E3A | E4A | E5A | E6A | E7A | E8A | E9A | F1A | F2A | F3A | F4A | F5A | F6A | F7A | F8A | F9A | G1A | G2A | G3A | G4A | G5A | G6A | G7A | G8A | G9A | H1A | H2A | H3A | H4A | H5A | H6A | H7A | H8A | H9A | I1A | I2A | I3A | I4A | I5A | I6A | I7A | I8A | I9A |
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | 062017009701000000000000008003061000080000000000042006006023007000000000030405010 | 862317549751984263394256178423861795685739421179542836546123987217698354938475612 | 332 | NULL | 6 | 2 | NULL | 1 | 7 | NULL | NULL | 9 | 7 | NULL | 1 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 8 | NULL | NULL | 3 | NULL | 6 | 1 | NULL | NULL | NULL | NULL | 8 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 4 | 2 | NULL | NULL | 6 | NULL | NULL | 6 | NULL | 2 | 3 | NULL | NULL | 7 | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | 3 | NULL | 4 | NULL | 5 | NULL | 1 | NULL | 8 | 6 | 2 | 3 | 1 | 7 | 5 | 4 | 9 | 7 | 5 | 1 | 9 | 8 | 4 | 2 | 6 | 3 | 3 | 9 | 4 | 2 | 5 | 6 | 1 | 7 | 8 | 4 | 2 | 3 | 8 | 6 | 1 | 7 | 9 | 5 | 6 | 8 | 5 | 7 | 3 | 9 | 4 | 2 | 1 | 1 | 7 | 9 | 5 | 4 | 2 | 8 | 3 | 6 | 5 | 4 | 6 | 1 | 2 | 3 | 9 | 8 | 7 | 2 | 1 | 7 | 6 | 9 | 8 | 3 | 5 | 4 | 9 | 3 | 8 | 4 | 7 | 5 | 6 | 1 | 2 |
+----+-----------------------------------------------------------------------------------+-----------------------------------------------------------------------------------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
region1 和 region9（两者 table 相同）
+--------+-----------+-----------+
| ID | Puz | Ans |
+--------+-----------+-----------+
| 427974 | 000000000 | 123458976 |
| 169852 | 000000000 | 123459678 |
| 162359 | 000000000 | 123468957 |
| 290352 | 000000000 | 123468975 |
| 418083 | 000000000 | 123469578 |
+--------+-----------+-----------+
samurai2（samurai3多了一个专栏Puz3）
+----+------+-------+-------+
| ID | Diff | Puz1 | Puz2 |
+----+------+-------+-------+
| 1 | 338 | 28005 | 45032 |
| 2 | 261 | 35934 | 60202 |
| 3 | 358 | 49688 | 61760 |
| 4 | 299 | 21243 | 45461 |
| 5 | 360 | 39237 | 56552 |
+----+------+-------+-------+
查询 Samurai x2 拼图和输出，x3 会有第三个 ID。
SELECT region9.ID, region1.ID FROM region9, region1 WHERE region9.Puz = region1.Puz AND region9.Ans = region1.Ans AND NOT EXISTS ( SELECT 1 FROM samurai2 AS c WHERE c.Puz1 = region9.ID AND c.Puz2 = region1.ID);
+--------+--------+
| ID | ID |
+--------+--------+
| 568557 | 33176 |
| 52551 | 567499 |
| 416691 | 567885 |
| 566193 | 472617 |
| 563401 | 567324 |
+--------+--------+
sudoku9x9 中使用的 ID 与 region1 和 region9 中的 ID 相关
根据@Strawberry 的评论研究标准化后。我重做了我的整个数据库，查看我对问题的最后编辑。使用新架构，我原来的问题很容易解决。
SELECT puz1.sudoku9x9_id, puz1.difficulty, puz2.sudoku9x9_id, puz2.difficulty, puz3.sudoku9x9_id, puz3.difficulty
FROM sudoku9x9 as puz1
INNER JOIN sudoku9x9 as puz2
INNER JOIN sudoku9x9 as puz3
WHERE
puz1.clue_9 = puz2.clue_1 AND puz1.region_9 = puz2.region_1 AND
puz2.clue_9 = puz3.clue_1 AND puz2.region_9 = puz3.region_1