Question

我正试图在mysql中检索匹配和不匹配的记录。

center_wise_test_rates:

lab_id   category_name   test_id   test_name           rate
------   -------------   --------  ---------           ------
2        Cardiology       9        Blood Sug           1200
2        Cardiology      10       Total Cholesterol    1500
2        Cardiology      11       HDL                  1100
2        Cardiology      12       LDL                  750

test_list

test_id  category_name       test_name
-------  -------------       ---------
9        Cardiology          Blood Sug
10       Cardiology          Total Cholesterol
11       Cardiology          HDL
12       Cardiology          LDL
57       Cardiology          abc

从基于category_name和lab_id的center_wise_test_rates和test_list表中，将获得匹配记录，但不匹配的记录，即测试名称'abc'未获得。

我的查询：

SELECT cwtr.lab_id
      ,cwtr.category_name
      ,cwtr.test_id
      ,cwtr.test_name
      ,cwtr.rate
FROM `center_wise_test_rates` AS cwtr
LEFT OUTER JOIN test_list AS tl ON tl.category_name = (SELECT DISTINCT category_name
                                                       FROM center_wise_test_rates 
                                                       WHERE category_name='Cardiology')
                                AND tl.test_id = cwtr.test_id
WHERE cwtr.lab_id = '2'
AND cwtr.category_name = 'Cardiology'

输出：

lab_id  category_name  test_id  test_name        rate
------   ------------  -------- ---------        ----
2        Cardiology       9     Blood Sug        1200
2        Cardiology      10    Total Cholesterol 1500
2        Cardiology      11       HDL            1100
2        Cardiology      12       LDL            750

预期输出：

 lab_id  category_name  test_id   test_name          rate
 ------  -------------  --------  ---------          ----
  2      Cardiology       9       Blood Sug          1200
  2      Cardiology      10       Total Cholesterol  1500
  2      Cardiology      11       HDL                1100
  2      Cardiology      12       LDL                 750
  2      Cardiology      57       abc                 Null

谢谢。

Answer 1

您所需要的只是左加入-

SELECT (SELECT lab_id
        FROM center_wise_test_rates
        WHERE category_name = tl.category_name
        LIMIT 1) lab_id
      ,tl.category_name
      ,tl.test_id
      ,tl.test_name
      ,cwtr.rate 
FROM test_list tl
LEFT JOIN center_wise_test_rates cwtr ON tl.test_id = cwtr.test_id
                                      AND tl.category_name = cwtr.category_name

Here是演示。

Answer 2

它将从TABLE1中选择条件是否匹配的所有值。

 SELECT coulmn1, column2 FROM TABLE1 LEFT JOIN TABLE2 ON TABLE1.ID= TABLE2.ID WHERE NAME = 'ABC'

如何在MySQL中检索匹配和不匹配的记录？

2 个答案: