我如何从SQL数据库值到使用C＃文本框？(How do I get values from a SQ

我创建一个预订管理系统，我有试图从SQL数据库获取数据并插入到一组我的应用程序的文本框的问题。

我想要显示的客户详细信息，当按钮被点击时，在一个DataGridView，但是当我点击该按钮，应用程序将引发与以下错误消息的异常;

无效的尝试时不存在数据读取。

我附上一个截图 ，我要查看客户详细信息屏幕，并为按钮，最终将显示在相应的文本框客户详细信息的代码。 任何帮助将不胜感激！

    SqlConnection sc = new SqlConnection("Data Source=localhost;Initial Catalog=LoginScreen;Integrated Security=True");
        SqlCommand com = new SqlCommand();
        com.Connection = sc;
        sc.Open();
        SqlDataReader read = (null);
        com.CommandText = ("select * from Pending_Tasks");
        read = com.ExecuteReader();
        CustID.Text = (read["Customer_ID"].ToString());
        CustName.Text = (read["Customer_Name"].ToString());
        Add1.Text = (read["Address_1"].ToString());
        Add2.Text = (read["Address_2"].ToString());
        PostBox.Text = (read["Postcode"].ToString());
        PassBox.Text = (read["Password"].ToString());
        DatBox.Text = (read["Data_Important"].ToString());
        LanNumb.Text = (read["Landline"].ToString());
        MobNumber.Text = (read["Mobile"].ToString());
        FaultRep.Text = (read["Fault_Report"].ToString());
        sc.Close();

Answer 1:

该生产线reader.Read()中缺少你的代码。 你应该添加它。 这是实际上是从数据库中读取数据的功能：

string conString = "Data Source=localhost;Initial Catalog=LoginScreen;Integrated Security=True";
SqlConnection con = new SqlConnection(conString);

string selectSql = "select * from Pending_Tasks";
SqlCommand com = new SqlCommand(selectSql, con);

try
{
    con.Open();

    using (SqlDataReader read = cmd.ExecuteReader())
    {
        while(reader.Read())
        {
            CustID.Text = (read["Customer_ID"].ToString());
            CustName.Text = (read["Customer_Name"].ToString());
            Add1.Text = (read["Address_1"].ToString());
            Add2.Text = (read["Address_2"].ToString());
            PostBox.Text = (read["Postcode"].ToString());
            PassBox.Text = (read["Password"].ToString());
            DatBox.Text = (read["Data_Important"].ToString());
            LanNumb.Text = (read["Landline"].ToString());
            MobNumber.Text = (read["Mobile"].ToString());
            FaultRep.Text = (read["Fault_Report"].ToString());
        }
    }
}
finally
{
    con.Close();
}

编辑：此代码假设你想要写的最后一条记录的文本框。 如果你想申请一个不同的场景，例如像以读取数据库中的所有记录，并更改texboxes数据，当您单击Next按钮，你应该创建和使用自己的型号，或者您也可以在数据表中存储数据并指给他们，如果你想以后。

Answer 2:

using (SqlConnection connection =  new SqlConnection("Data Source=localhost;Initial Catalog=LoginScreen;Integrated Security=True"))
{
    SqlCommand command =
    new SqlCommand("select * from Pending_Tasks WHERE CustomerId=...", connection);
    connection.Open();

    SqlDataReader read= command.ExecuteReader();

    while (read.Read())
    {
        CustID.Text = (read["Customer_ID"].ToString());
        CustName.Text = (read["Customer_Name"].ToString());
        Add1.Text = (read["Address_1"].ToString());
        Add2.Text = (read["Address_2"].ToString());
        PostBox.Text = (read["Postcode"].ToString());
        PassBox.Text = (read["Password"].ToString());
        DatBox.Text = (read["Data_Important"].ToString());
        LanNumb.Text = (read["Landline"].ToString());
        MobNumber.Text = (read["Mobile"].ToString());
        FaultRep.Text = (read["Fault_Report"].ToString());
    }
    read.Close();
}

请确保您有在查询数据：SELECT * FROM Pending_Tasks和您正在使用“使用System.Data.SqlClient的;”

Answer 3:

read = com.ExecuteReader()

SqlDataReader具有功能Read()读取从查询结果的下一行，并返回一个bool是否找到了下一行来读取或没有。 所以，你需要检查之前，你实际上是从你的读者（这永远只是获取当前行是得到列Read()了）。 或者最好做一个循环while(read.Read())如果您的查询返回多行。

Answer 4:

如果你想显示从数据库中单值接入到文本框，请参阅下面的代码：

SqlConnection con=new SqlConnection("connection string");
SqlCommand cmd=new SqlConnection(SqlQuery,Con);
Con.Open();
TextBox1.Text=cmd.ExecuteScalar();
Con.Close();

要么

SqlConnection con=new SqlConnection("connection string");
SqlCommand cmd=new SqlConnection(SqlQuery,Con);
Con.Open();
SqlDataReader dr=new SqlDataReadr();
dr=cmd.Executereader();
if(dr.read())
{
    TextBox1.Text=dr.GetValue(0).Tostring();
}
Con.Close();

Answer 5:

进行连接并打开它。

con = new OracleConnection("Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=<database_name>)));User Id =<userid>; Password =<password>");
con.Open();

写的选择查询：

string sql = "select * from Pending_Tasks";

创建一个命令对象：

OracleCommand cmd = new OracleCommand(sql, con);

执行命令，并把结果在一个对象来读取它。

OracleDataReader r = cmd.ExecuteReader();

现在开始从中读取。

while (read.Read())
{
 CustID.Text = (read["Customer_ID"].ToString());
 CustName.Text = (read["Customer_Name"].ToString());
 Add1.Text = (read["Address_1"].ToString());
 Add2.Text = (read["Address_2"].ToString());
 PostBox.Text = (read["Postcode"].ToString());
 PassBox.Text = (read["Password"].ToString());
 DatBox.Text = (read["Data_Important"].ToString());
 LanNumb.Text = (read["Landline"].ToString());
 MobNumber.Text = (read["Mobile"].ToString());
 FaultRep.Text = (read["Fault_Report"].ToString());
}
read.Close();

添加这也采用Oracle.ManagedDataAccess.Client;

文章来源: How do I get values from a SQL database into textboxes using C#?