Question

美好的一天，

我有： -

 SELECT MAX(register_number) AS "Next-6-months-register-number" 
    FROM gypsum WHERE test_frequency ='6'

我想在同一个查询中返回test_frequency ='3'和'12'的值。这可能吗？谢谢GWS。

Answer 1

是的，这是可能的。使用GROUP BY获取每个组的最大值：

SELECT test_frequency, MAX(register_number) AS "Max-register-number"
FROM gypsum
WHERE test_frequency IN ('3', '6', '12')
GROUP BY test_frequency

Answer 2

SELECT 
  MAX(CASE WHEN test_frequency = '3' THEN register_number END) 
      AS "Next-3-months-register-number",
  MAX(CASE WHEN test_frequency = '12' THEN register_number END) 
      AS "Next-12-months-register-number",
  MAX(CASE WHEN test_frequency = '6' THEN register_number END) 
      AS "Next-6-months-register-number",
  MAX(register_number) AS "Next-6-months-register-number" 
FROM gypsum

Answer 3

试试这个

SELECT MAX(CASE 
                WHEN test_frequency ='6' THEN register_number 
           ELSE NULL END) AS "Next-6-months-register-number" ,
      MAX(CASE 
                WHEN test_frequency ='3' THEN register_number 
           ELSE NULL END) AS "Next-3-months-register-number" ,
     MAX(CASE 
                WHEN test_frequency ='12' THEN register_number 
           ELSE NULL END) AS "Next-12-months-register-number" 
FROM gypsum

Answer 4

获取所有test_frequency的最大值

SELECT test_frequency ,MAX(register_number) AS "Next-6-months-register-number" 
FROM gypsum 
group by test_frequency

OR

SELECT MAX(register_number) AS "Next-6-months-register-number" 
FROM gypsum WHERE test_frequency in('6','3','12')
group by test_frequency

Answer 5

您应该只需使用 OR 关键字添加额外参数。

SELECT MAX(register_number) AS "Next-6-months-register-number" FROM gypsum 
WHERE test_frequency ='6'
or 
test_frequency ='3'
or
test_frequency ='12'

Answer 6

在这里，您可以添加测试频率..（'3'，'12）..或从查询中选择：

SELECT test_frequency, MAX(register_number) AS "Max-register-number"
FROM gypsum
WHERE test_frequency IN ('3','12')
GROUP BY test_frequency

SELECT test_frequency, MAX(register_number) AS "Max-register-number"
FROM gypsum
WHERE test_frequency IN (select frequency_colname from tablename where colname=value)
GROUP BY test_frequency

同一查询中的多个max（）

6 个答案: