Question

您好我正在使用sqlite。当我在数据中查找未赋值的平均值时，我已经在sqlite中存储了一些字段。

cursor = database.rawQuery("Select '"+start+"' as dateadded ,AVG('ch4') as 'ch4',AVG('c2h2') as 'c2h2',AVG('c2h4') as 'c2h4' where dateAdded between '"+start+"' and '"+end+"' and '"+edd+"' = '"+equipid+"' ",null);

我这样写的是返回值，但这不正确。我认为问题是我没有写任何表名。

当我在sqlite中执行只返回dateadded并且remaning all的代码为空时。

Select '02-07-14 11:58' as dateadded ,AVG('ch4') as ch4,AVG('c2h2') as c2h2,AVG('c2h4') as c2h4 where dateAdded between '02-07-14 11:58' and '03-07-14 11:58' and "equipid" = '2'

如果我写代码

Select '02-07-14 11:58' as dateadded ,AVG('ch4') as ch4,AVG('c2h2') as c2h2,AVG('c2h4') as c2h4 where dateAdded between '02-07-14 11:58' and '03-07-14 11:58' and "equipid" = '2' FROM dgadata

dgadata是表名。但那显示出类似的内容

Error:near "FROM": syntax error:

那么请你告诉我如何在android sqlite中编写平均值的查询。

谢谢

香卡

Answer 1

你的语法错误。你用

SELECT ... WHERE ...FROM...

正确

SELECT .... FROM ... WHERE ...

Answer 2

选择＆＃39; 02-07-14 11：58＆＃39;作为日期添加，AVG（＆＃39; ch4＆＃39;）为ch4，AVG（＆＃39; c2h2＆＃39;）为c2h2，AVG（＆＃39; c2h4＆＃39;）为c2h4，其中date添加在＆＃39之间; 02-07-14 11:58＆＃39;和＆＃39; 03-07-14 11:58＆＃39;和＆＃34; equipid＆＃34; =＆＃39; 2＆＃39;

在此查询中请在tablename之前添加

离

选择＆＃39; 02-07-14 11：58＆＃39;作为datename从tablename添加日期在＆＃39; 02-07-14 11:58＆＃39;之间和＆＃39; 03-07-14 11:58＆＃39;和＆＃34; equipid＆＃34; =＆＃39; 2＆＃39;

如何从我的sqlite中获取列的平均值形式？

2 个答案: