我在 StackOverflow 上查看了各种主题,但无法找到适合我问题的解决方案。这是我得到的:
我有两个数据库表。一个表应该是某种引用模型,看起来类似于此示例:
+----+----------------+----------------+----------------+-----------------+
| ID | FIELD1 | FIELD2 | FIELD3 | FIELD 4 |
+----+----------------+----------------+----------------+-----------------+
| 1 | Value1_Field_1 | Value1_Field_2 | Value1_Field_3 | Value1_Field_4 |
| 2 | Value2_Field_1 | Value2_Field_2 | Value2_Field_3 | Value2_Field_4 |
| 3 | Value3_Field_1 | Value3_Field_2 | Value3_Field_3 | Value3_Field_4 |
| 4 | Value4_Field_1 | Value4_Field_2 | Value4_Field_3 | Value4_Field_4 |
| 5 | Value5_Field_1 | Value5_Field_2 | Value5_Field_3 | Value5_Field_4 |
+----+----------------+----------------+----------------+-----------------+
现在我将新数据输入到第二个表中。这些数据可以具有相同的值以及相同的行数。但也可能发生某些数据具有更多行或行内的值不同的情况。这是另一个表格示例,其中我有多一行并且两个值不同:
+----+----------------+-----------------+-----------------+----------------+
| ID | FIELD1 | FIELD2 | FIELD3 | FIELD 4 |
+----+----------------+-----------------+-----------------+----------------+
| 1 | Value1_Field_1 | Value1_Field_2 | Value1_Field_3 | Value1_Field_4 |
| 2 | Value2_Field_1 | Value2_Field_2 | Value2_Field_3 | Value2_Field_4 |
| 3 | Value3_Field_1 | Value3_Field_2 | Value3_NEWVALUE | Value3_Field_4 |
| 4 | Value4_Field_1 | Value4_Field_2 | Value4_Field_3 | Value4_Field_4 |
| 5 | Value5_Field_1 | Value5_NEWVALUE | Value5_Field_3 | Value5_Field_4 |
| 6 | Value6_Field_1 | Value6_Field_2 | Value6_Field_3 | Value6_Field_4 |
+----+----------------+-----------------+-----------------+----------------+
我正在寻找一个 SQL 语句来比较这两个表并列出所有不同的记录。在我上面的示例中,SQL 语句应该返回这些信息:
+----+----------------+-----------------+-----------------+----------------+
| ID | FIELD1 | FIELD2 | FIELD3 | FIELD 4 |
+----+----------------+-----------------+-----------------+----------------+
| 3 | | | Value3_NEWVALUE | |
| 5 | | Value5_NEWVALUE | | |
| 6 | Value6_Field_1 | Value6_Field_2 | Value6_Field_3 | Value6_Field_4 |
+----+----------------+-----------------+-----------------+----------------+
这是我迄今为止尝试过的:
SELECT distinct FIELD1, FIELD2, FIELD3, FIELD4 from table_references
union
SELECT distinct FIELD1, FIELD2, FIELD3, FIELD4 from table_new_data
该语句返回所有行,但仅返回一次。这不是我要找的。我也用这段代码尝试过:
SELECT FIELD1, FIELD2, FIELD3, FIELD4
FROM (
SELECT FIELD1, FIELD2, FIELD3, FIELD4 FROM table_references
UNION ALL
SELECT FIELD1, FIELD2, FIELD3, FIELD4 FROM table_new_data
) tbl
GROUP BY FIELD1
HAVING count(*) = 1
ORDER BY FIELD1
该代码仅返回第 6 行,但不显示 ID 3 和 5 内的新值。
任何帮助将不胜感激。提前致谢!
编辑: 根据@Madhur Bhaiya 解决方案,我犯了一个错误。输出应如下所示:
+----+----------------+-----------------+-----------------+----------------+
| ID | FIELD1 | FIELD2 | FIELD3 | FIELD 4 |
+----+----------------+-----------------+-----------------+----------------+
| 3 | Value3_Field1 | Value3_Field2 | Value3_NEWVALUE | Value3_Field4 |
| 5 | Value5_Field1 | Value5_NEWVALUE | Value5_Field3 | Value5_Field4 |
| 6 | Value6_Field_1 | Value6_Field_2 | Value6_Field_3 | Value6_Field_4 |
+----+----------------+-----------------+-----------------+----------------+
因此,我还需要受影响行中值不同的所有值。
最佳答案
我们可以使用LEFT JOIN
来比较两个表,然后使用If()
等条件函数来获取相应的值:
查询
SELECT tnew.*
FROM table_new_data AS tnew
LEFT JOIN table_references AS told
ON told.ID = tnew.ID
WHERE (told.ID IS NOT NULL AND
(tnew.FIELD1 <> told.FIELD1 OR
tnew.FIELD2 <> told.FIELD2 OR
tnew.FIELD3 <> told.FIELD3 OR
tnew.FIELD4 <> told.FIELD4)
) OR
told.ID IS NULL;
结果
| ID | FIELD1 | FIELD2 | FIELD3 | FIELD4 |
| --- | -------------- | --------------- | --------------- | -------------- |
| 3 | Value3_Field_1 | Value3_Field_2 | Value3_NEWVALUE | Value3_Field_4 |
| 5 | Value5_Field_1 | Value5_NEWVALUE | Value5_Field_3 | Value5_Field_4 |
| 6 | Value6_Field_1 | Value6_Field_2 | Value6_Field_3 | Value6_Field_4 |
关于mysql - 比较两个数据库表的值 -> MySQL,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53852022/