mssql 将 varchar 转换为 float [英] mssql convert varchar to float

问题描述

我的字段值 productlength 为 0.123.这是一个视图，数据类型为 varchar.

I have a field value productlength of 0.123. This is from a view and has a data type of varchar.

我需要将其转换为浮点数或数值，以便进行数学比较.

I need to convert it to a float or numeric value so as o perform math comparisons.

转换(浮点数，产品长度)和cast(productlength as float) 都不起作用.

convert(float,productlength) and cast(productlength as float) both do not work.

error varchar cant be convert to float 或类似的东西.

从我读到的 varchar 根本不能转换为数字字符串?

From what I have read varchar can simply not be converted to a numeric string?

有什么巧妙的办法解决这个问题?

Any clever ways around this?

推荐答案

你可以将varchars转换为float，你可以按照你表达的方式来做.您的 varchar 不能是数值.里面一定有别的东西.您可以使用 IsNumeric 对其进行测试.看到这个:

You can convert varchars to floats, and you can do it in the manner you have expressed. Your varchar must not be a numeric value. There must be something else in it. You can use IsNumeric to test it. See this:

declare @thing varchar(100)

select @thing = '122.332'

--This returns 1 since it is numeric.
select isnumeric(@thing)

--This converts just fine.
select convert(float,@thing)

select @thing = '122.332.'

--This returns 0 since it is not numeric.
select isnumeric(@thing)

--This convert throws.
select convert(float,@thing)

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