C＃中的SQL查询语法？ [英] Sql query syntax in C#?

问题描述

我正在尝试在桌面上运行查询，但一直收到错误：

参数化查询'（@TourName char （8000））更新ToursTbl SET可用性=（可'期望参数'@TourName'，未提供。

我猜它与我如何提供@TourName参数有关.Heres my code任何帮助??

 for（int i = 0; i< bookedToursArray.Length; i ++）
 {
 //命令更新巡视表中可用巡视的数量
 SqlCommand cmd2 = new SqlCommand（ ）; 
 cmd2.CommandText =UPDATE ToursTbl SET Availability =（Availability-1）WHERE TourName ='@ CityName'; 
 cmd2.Parameters.Add（@ TourName，SqlDbType.Char）。 Value = bookedToursArray [i]; 
 
 cmd2.Connection = conn; 
 
 conn.Open（）; 
 
 cmd2.ExecuteNonQuery （）; 
 
 conn.Close（）; 
} 
 

我尝试过：



问题似乎是我的语法

解决方案

请参阅

 cmd2.CommandText = < span class =code-string>  UPDATE ToursTbl SET Availability =（Availability-1）WHERE TourName ='@TourName'; 

使用参数化查询时，会为您添加单引号。该行应为

 cmd2.CommandText =   UPDATE ToursTbl SET Availability =（Availability-1 ）WHERE TourName = @TourName; 

你的下一个问题是

 cmd2.Parameters.Add（  @ TourName，SqlDbType.Char）.Value = bookedToursArray [i]; 

不要使用添加 - 将其更改为

 cmd2.Parameters.AddWithValue（  @TourName，bookedToursArray [I]）; 

I'm trying to run a query on a table but keep getting the error:

The parameterized query '(@TourName char(8000))UPDATE ToursTbl SET Availability = (Availa' expects the parameter '@TourName', which was not supplied.

I guessing its to do with how I've provided the @TourName parameter. Heres my code Any help??

for (int i = 0; i < bookedToursArray.Length; i++)
           {
               //command to update the number of available tours in the tours table
               SqlCommand cmd2 = new SqlCommand();
               cmd2.CommandText = "UPDATE ToursTbl SET Availability = (Availability-1) WHERE TourName = '@TourName'";
               cmd2.Parameters.Add("@TourName", SqlDbType.Char).Value = bookedToursArray[i];

               cmd2.Connection = conn;

               conn.Open();

               cmd2.ExecuteNonQuery();

               conn.Close();
           }

What I have tried:

The problem seems to be my syntax

解决方案

See the line

cmd2.CommandText = "UPDATE ToursTbl SET Availability = (Availability-1) WHERE TourName = '@TourName'";

When using parameterized queries the single-quotes are added for you. That line should be

cmd2.CommandText = "UPDATE ToursTbl SET Availability = (Availability-1) WHERE TourName = @TourName";

Your next problem is with

cmd2.Parameters.Add("@TourName", SqlDbType.Char).Value = bookedToursArray[i];

Don't use Add - change it to

cmd2.Parameters.AddWithValue("@TourName",bookedToursArray[i]);

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