问题描述
考虑这样一个场景，您希望从表中提取最后 x 个条目.我们想要的列包含有关产品的推荐.出于性能原因，我们只想从推荐中获取前 50 个字符.该列名为 TestimonialText，类型为 text.
Consider a scenario where you'd like to pull the last x entries from a table. The column we want contains testimonials about a product. For performance reasons, we only want to grab the first 50 characters from the testimonial. The column is named TestimonialText and is of type text.
考虑这个 T-SQL 的精简片段:
Consider this condensed snippet of T-SQL:
SELECT TOP 10
C.FirstName + ' ' + C.LastName AS CustomerName
,LEFT(C.TestimonialText,50) AS TestimonialSnippet
,C.TestimonialDate
FROM Customer AS C
ORDER BY C.TestimonialDate DESC
这会产生一个错误:
参数数据类型文本无效左函数的参数 1.
Argument data type text is invalid for argument 1 of left function.
问题:如何只提取 text 或 ntext 列的前几个 n 个字符?
Question: how to extract just the first few n characters of the text or ntext column?
推荐答案
我认为 SUBSTRING 是更好的选择.试试这个:
I think SUBSTRING would be a better choice. Try this:
SELECT TOP 10
C.FirstName + ' ' + C.LastName AS CustomerName
,SUBSTRING(C.TestimonialText,1,50) AS TestimonialSnippet
,C.TestimonialDate
FROM Customer AS C
ORDER BY SUBSTRING(C.TestimonialText,1,50) DESC
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