在 C# 中从 SQL 数据库中读取值

Reading values from SQL database in C#(在 C# 中从 SQL 数据库中读取值)

问题描述

我刚开始学习 C#，我可以毫无问题地将数据写入数据库.但是我在阅读时遇到了问题，SQL 执行得很好，但是我在存储它时遇到了问题.我将如何存储应该返回的四列，然后将它们显示为消息框?谢谢.

i have just started learning C# and i can write data to the database without a problem. But i'm having problems with reading, the SQL executes fine but i'm having issues with storing it. How would i store the four columns that should be returned and then show them as a message box? Thanks.

SqlCommand myCommand = new SqlCommand("select * from Requests where Complete = 0", myConnection);
SqlDataReader myReader = myCommand.ExecuteReader();
while (myReader.Read())

Console.WriteLine(myReader["Username"].ToString());
Console.WriteLine(myReader["Item"].ToString());
Console.WriteLine(myReader["Amount"].ToString());
Console.WriteLine(myReader["Complete"].ToString());

推荐答案

一个问题是while后面少了大括号

One problem is missing braces after the while

while (myReader.Read())
{  // <<- here
    Console.WriteLine(myReader["Username"].ToString());
    Console.WriteLine(myReader["Item"].ToString());
    Console.WriteLine(myReader["Amount"].ToString());
    Console.WriteLine(myReader["Complete"].ToString());
}  // <<- here

如果你跳过大括号，每个循环只处理第一行，其余的将在循环后处理，然后 myReader 超过最后一行.

if you skip the braces only the first line will be processed in each loop, the rest will be processed after the loop, then myReader is past the last row.

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