像多列查询一样 [英] Like query with multiple columns
问题描述
select * from tblBusinessCategory as b
inner join tblUser as u
on b.BusinessID=u.BusinessCategoryId
inner join tblAddress as a
on u.AddressId=a.AddressID
where u.BusinessCategoryId in (select BusinessCategory from tblBusinessCategory where BusinessCategory LIKE '%d%')
执行此查询时我得到了
＃1）将nvarchar值'Dentist'转换为数据类型int时转换失败。如何解决这个问题??
＃2）如何对多列执行类似操作？
＃3）这可以在mvc4控制器中调用此查询吗？
While doing this query i got
#1 ) Conversion failed when converting the nvarchar value 'Dentist' to data type int. how to solve this ??
#2 ) How to perform like operation on multiple columns??
#3 ) Is this possible to call this query in mvc4 controller ??
推荐答案
如果您可以直接使用条件，为什么要使用子查询来过滤数据？！？
Why to use subquery to filter data, if you can use a "condition" directly?!?
select *
from tblBusinessCategory as b
inner join tblUser as u on b.BusinessID=u.BusinessCategoryId
inner join tblAddress as a on u.AddressId=a.AddressID
where b.BusinessCategory LIKE '%d%'
请看一下这篇优秀文章： SQL连接的可视化表示 [ ^ ]了解join的工作方式。
＃1）将nvarchar值'Dentist'转换为数据类型int时转换失败。如何解决这个问题??
BusinessCategoryId 与 BusinessCategory 。为了能够获得正确的数据，你必须写：
Please, take a look at this excellent article: Visual Representation of SQL Joins[^] to understand how join's work.
#1 ) Conversion failed when converting the nvarchar value 'Dentist' to data type int. how to solve this ??
BusinessCategoryId is not the same as BusinessCategory. To be able to get proper data, you have to write:
where u.BusinessCategoryId in (select BusinessCategoryId from tblBusinessCategory where BusinessCategory LIKE '%d%')
但是！由于性能问题，我不建议使用这样的子查询！
＃2）如何对多列执行类似操作？
写出正确的WHERE语句！
But! I do not recommend to use subquery like this, because of performance issue!
#2 ) How to perform like operation on multiple columns??
Write proper WHERE statement!
WHERE ((Column1 Like '%a' AND (Column2 = 1 OR Column3 = 2)
＃3）这可以在mvc4控制器中调用此查询吗？
我不明白你...;（
#3 ) Is this possible to call this query in mvc4 controller ??
I do not understand you... ;(
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