Question

我想查询具有不同数据类型的几个变量的数据库。

我的查询如下：

SELECT var1, var2,  
       SUM( CASE WHEN var3 ='2008' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS 'A1_U18_7',
       SUM( CASE WHEN var3='2015' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS 'A34_U15_0',
       CASE WHEN var3 = '2015' AND var4 = 'A0_RISE' THEN var5 ELSE 0 END AS 'A0_RISE'
FROM dataset1
GROUP BY var1

实际上我不需要总结前两个查询的结果，否则我会得到一个＆＃34; 0＆＃34;作为输出。总之，我得到了正确的答案。

然而，在＆＃34; A0_RISE＆＃34;的情况下，这种解决方法是不可行的。因为数据类型是文本。没有SUM函数，我在这里得到了输出＆＃34; 0＆＃34;也是。

我如何才能获得所有变量的输出？如果你对双打的SUM解决方案有更好的想法，我会非常感谢你在这里！

Answer 1

也许使用Max？

SELECT var1, var2,  
       SUM( CASE WHEN var3 ='2008' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS 'A1_U18_7',
       SUM( CASE WHEN var3='2015' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS 'A34_U15_0',
       MAX(CASE WHEN var3 = '2015' AND var4 = 'A0_RISE' THEN var5 ELSE '' END ) AS 'A0_RISE'
FROM dataset1
GROUP BY var1

Answer 2

将 var5转换为整数，就像这个group by var1,var2一样，并在组中添加var2，如同SELECT var1, var2, SUM( CASE WHEN var3 ='2008' AND var4='A1_U18' THEN CAST(var5 AS UNSIGNED) ELSE 0 END ) AS 'A1_U18_7', SUM( CASE WHEN var3='2015' AND var4='A1_U18' THEN CAST(var5 AS UNSIGNED) ELSE 0 END ) AS 'A34_U15_0', CASE WHEN var3 = '2015' AND var4 = 'A0_RISE' THEN CAST(var5 AS UNSIGNED) ELSE 0 END AS 'A0_RISE' FROM dataset1 GROUP BY var1,var2

if [ "$foo" != "1" ]
then
    echo Success
fi

Answer 3

也许是group_concat()？

SELECT var1, 
       SUM(CASE WHEN var3 ='2008' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS A1_U18_7,
       SUM( CASE WHEN var3='2015' AND var4='A1_U18' THEN var5 ELSE 0 END ) AS A34_U15_0,
       GROUP_CONCAT(CASE WHEN var3 = '2015' AND var4 = 'A0_RISE' THEN var5 END) AS A0_RISE
FROM dataset1
GROUP BY var1;

请勿在{{1}}中加入var2，除非您还将其包含在SELECT中。

MySQL查询具有多个条件而没有WHERE

3 个答案: