Question

Tabel_1：

Id    test_id  testname    passfail
1      1001       test1      pass
2      1001       test2      fail
3      1002       test11     pass
4      1002       test12     pass
5      1003       test21     fail
6      1003       test22     fail

Tabel_2：

Id    test_id  testname    passfail
1      1001       test1      pass
2      1001       test2      pass
3      1001       test3      pass
4      1002       test11     pass
6      1002       test13     fail
7      1002       test13     fail

Tabel_3：

Id    test_id  testname    passfail
4      1002       test11     pass
5      1002       test12     pass
6      1003       test31     fail
7      1003       test32     fail

Tabel_4：

Id    test_id  testname    passfail
1      1001       test1      pass
2      1001       test2      pass
3      1001       test3      pass
4      1003       test11     pass
5      1003       test12     pass

我想检查所有表（Tabel_1，Tabel_2，Tabel_3，Tabel_4）中的passfail列，并使用特定的test_id（如1001）或任何test_id。如果任何行失败，因为passfail列属于id，如1001那么查询将只返回一次失败或者在passfail列中找不到失败属于特定的test_id然后查询将只返回passfail colomn传递一次。

Answer 1

您可以使用CASE这样的表达式：

SELECT CASE 
          WHEN EXISTS (SELECT 1
                       FROM Table1
                       WHERE test_Id = 1001 AND passfail = 'fail'
                       UNION 
                       SELECT 1
                       FROM Table2
                       WHERE test_Id = 1001 AND passfail = 'fail'
                       UNION 
                       SELECT 1
                       FROM Table3
                       WHERE test_Id = 1001 AND passfail = 'fail'
                       UNION 
                       SELECT 1
                       FROM Table4
                       WHERE test_Id = 1001 AND passfail = 'fail')
           THEN 'fail'
           ELSE 'pass'
         END AS flag;

此SELECT语句返回始终一行：如果四个表中任何一个中至少有一行有passfail = 'fail'，则返回'fail'，否则返回'pass'。

Answer 2

您可以使用UNION DISTINCT：

组合每个SELECT的结果

SELECT test_id FROM Table_1 WHERE passfail = 'fail'
UNION DISTINCT
SELECT test_id FROM Table_2 WHERE passfail = 'fail'
UNION DISTINCT
SELECT test_id FROM Table_3 WHERE passfail = 'fail'
UNION DISTINCT
SELECT test_id FROM Table_4 WHERE passfail = 'fail'

Answer 3

您可以按UNION合并结果，并使用GROUP BY按某些字段进行分组：

List

结果：

Test

如果要将test_id添加到SELECT语句，则只能获得ID：

public int indexOf(Object o) {
    if (o == null) {
        for (int i = 0; i < size; i++)
            if (elementData[i]==null)
                return i;
    } else {
        for (int i = 0; i < size; i++)
            if (o.equals(elementData[i])) // o in your case is a String while
                                          // elementData[i] is a Test
                                          // so String's equals returns false
                return i;
    }
    return -1;
}

结果：SELECT * FROM ( SELECT * FROM t1 WHERE passfail = 'pass' UNION SELECT * FROM t2 WHERE passfail = 'pass' UNION SELECT * FROM t3 WHERE passfail = 'pass' UNION SELECT * FROM t4 WHERE passfail = 'pass' ) as t GROUP BY test_id;

如果删除GROUP BY：

，您还可以获取

1   1001    test1   pass
4   1002    test12  pass
8   1003    test32  pass
3   10015   test11  pass

值的所有行

SELECT test_id FROM
  (
  SELECT * FROM t1 WHERE passfail = 'pass'
  UNION
  SELECT * FROM t2 WHERE passfail = 'pass'
  UNION
  SELECT * FROM t3 WHERE passfail = 'pass'
  UNION
  SELECT * FROM t4 WHERE passfail = 'pass'
) as t
GROUP BY test_id;

结果：

1001, 1002, 1003, 10015

检查具有特定ID的4个不同表中的列值以及失败的返回通过

3 个答案: