如何在C# - Windows Forms中使用SQL代码连接3个表

using System.Data.SqlClient;

string connectionString = "Data Source=your_server;Initial Catalog=your_database;User ID=your_username;Password=your_password";
SqlConnection connection = new SqlConnection(connectionString);
connection.Open();

string query = "SELECT * FROM Table1 JOIN Table2 ON Table1.ID = Table2.Table1ID JOIN Table3 ON Table2.ID = Table3.Table2ID";
SqlCommand command = new SqlCommand(query, connection);

SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
    // 处理查询结果
    // 例如，可以使用reader.GetInt32、reader.GetString等方法获取特定列的值
}
reader.Close();

connection.Close();