如何从DataTable列中仅选择最后500个单词并在C＃中的相同DataTable中更新它 [英] How to select only last 500 words from column of DataTable and update it in the same DataTable in C#

问题描述

我在DataTable中调用C＃Form上的数据库，它有一个包含超过3K-4K单词的Text数据的列，但我只需要该列的最后500个单词，列索引是第6个，所以如何更新该列中只有500字？



我尝试过这样的事情：

I'm calling the DB on C# Form in a DataTable, it has a column with Text data which more than 3K-4K words but I only need last 500 words from that column and the column index is 6th so how to update only last 500 words in that column?

I tried something like this:

SqlDataAdapter da = new SqlDataAdapter("select * from Table1", sqlCon);
DataTable dtMainSQLData = new DataTable();
                if (dtMainSQLData.Columns.Contains("DA_ArticleDetails"))
                {
                    //not sure what to code here
                    //but the code should select last 500 words from the column
                    //and update them in the same column
               }
//fill the data table with the data from SELECT query
 da.Fill(dtMainSQLData);

请帮助!!

Help Please!!

推荐答案

这是适合的你：

This is something that suits to you:

Create FUNCTION [dbo].[fnGetWords](@pStr varchar(max), @pWords int)
RETURNS VARCHAR(MAX)
AS
BEGIN
     DECLARE @lPos int, @lCtr int
     SET @lCtr = Len(@pStr)
     SET @lPos = 0
     WHILE @lCtr>=@pWords
     BEGIN
          SET @lPos = CHARINDEX(' ',  @pStr, @lPos + 1)
          SET @lCtr = @lCtr - 1
     END
     RETURN SUBSTRING(@pStr,@lPos, Len(@pStr)-1)
END


select dbo.fnGetWords('This is getting words from right',-2)

< br / >
给出最后一个单词right。您可以根据自己的标准更改逻辑。

gives the last word "right". you can change the logic as per your criteria.

一块蛋糕

从表1中选择RIGHT（colname，500）



您也可以使用Left，

注意：即使没有足够的数据，它们也不会抛出任何错误。

Piece of cake
select RIGHT(colname, 500)from Table1

You can also use Left ,
Note : Both of them won't throw any error even if there is not enough data available.

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