如何在c＃中的select查询中获取字符串值 [英] how to get the string value in select query in c#

问题描述

我有一组字符串值，我想使用c＃中的select查询中的值。怎么弄它



string dbdate = string.Join（，，dat）;



string Sql = @select * from prg_detail where service_id ='+ comboBox1.SelectedValue +'and date in（@param）;

conn.Open（）;

SqlCommand cmd = new SqlCommand（Sql，conn）;

SqlDataAdapter dbad = new SqlDataAdapter（cmd）;

cmd.Parameters.AddWithValue（@ param，dbdate ）;





DataTable dt3 = new DataTable（）;

dbad.Fill（dt3）;



但它不起作用

解决方案

你不能这样做。

有一个SQL子句可以提供帮助：

  SELECT  *  FROM  MyTable  WHERE  Id  IN （ 1 ， 2 ， 3 ， 4 ）

将返回列表中包含任何一个id值的行，您可以将其用于日期：但不能使用参数值。

您可以说：

  string  Sql =  @  SELECT * FROM prg_detail WHERE service_id =' + comboBox1.SelectedValue +  '和日期IN（ + dbdate +  ） ; 

但是......您需要确保每个日期都正确格式化（最好是yyyy-MM-dd）并用引号分隔。

一种方法是：

  string  dbdate =  ' +  string  .Join（ '，'，dat）+  ; 

如果您的日期格式正确。

i have set of string values i want use the values in the select query in c#. how to get it

string dbdate=string.Join(",", dat);

string Sql = @"select * from prg_detail where service_id = '" + comboBox1.SelectedValue + "' and date in (@param)";
conn.Open();
SqlCommand cmd = new SqlCommand(Sql, conn);
SqlDataAdapter dbad = new SqlDataAdapter(cmd);
cmd.Parameters.AddWithValue("@param", dbdate);


DataTable dt3=new DataTable();
dbad.Fill(dt3);

but its not working

解决方案

You can't do it like that.
There is a SQL clause that will help:

SELECT * FROM MyTable WHERE Id IN (1, 2, 3, 4)

Will returns rows with any one of the id values in the list, and you can use this for dates: but you can't use parameter values.
You could say:

string Sql = @"SELECT * FROM prg_detail WHERE service_id = '" + comboBox1.SelectedValue + "' AND date IN (" + dbdate + ")";

But...you would need to make sure that each of your dates is properly formated (preferably yyyy-MM-dd) and delimited by quotes.
One way to do that is:

string dbdate="'" + string.Join("','", dat) + "'";

If your dates come pre formatted correctly.

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