c＃.net中的执行查询问题 [英] executenonquery problem in c#.net

问题描述

我在执行非查询sql语句时遇到问题。请记住，我还是.NET框架和MySQL的新手。这是我的代码。

 private void Binding（）
 {
 string connStr =datasource = localhost; port = 3306;用户名=根;密码=根;; 
 conn = new MySqlConnection（connStr）; 
 MySqlCommand command = conn.CreateCommand（）; 
 try 
 {
 string database = schemaForm.getData; 
 dtable = new DataTable（）; 
 bindingSource = new BindingSource（）; ; 
 
 conn.Open（）; 
 command.CommandText =SELECT Metabolite_Name+ 
FROM+ database + 
.Metabolites WHERE+ 
MetaboliteID IN（'met1'，'met2'）; ; 
 command.ExecuteNonQuery（）; 
 sqlData.SelectCommand = command; 
 sqlData.Fill（dtable）; 
 bindingSource.DataSource = dtable; 
 dbMetName.DataSource = dtable; 
 dtable.Columns.Add（代谢物名称）; 
 dbMetName.DataSource = dtable; 
 conn.Close（）; 
} 
 catch（Exception ex）
 {
 MessageBox.Show（ex.Message）; 
} 
} 
 

从getData表单传递值

使用System; 
使用System.Collections.Generic;使用System.ComponentModel 
; 
使用System.Data;使用System.Drawing 
; 
使用System.Linq; 
使用System.Text; 
使用System.Windows.Forms; 
 
命名空间DynamicSimulator_v2 
 {
 public partial class SchemaName：Form 
 {
 private static string data; 
 public Sc​​hemaName（）
 {
 InitializeComponent（）; 
} 
 
 private void btnCancel_Click（object sender，EventArgs e）
 {
 this.Hide（）; 
} 
 
 private void btnOK_Click（object sender，EventArgs e）
 {
 data = txtDB.Text; 
 this.Hide（）; 
} 
 
公共字符串getData 
 {
 set 
 {
 data = txtDB.Text; 
} 
获得
 {
返回数据; 
} 
} 
} 
} 

错误显示我的查询是错误。我非常确定查询是正确的，因为我在MySQL脚本上测试它。我试图在datagridview中显示它。 dbMetName是datagridview。

解决方案

Quote：

command.ExecuteNonQuery（）;

用于插入/更新



您应该使用ExecuteReader并将数据加载到DataTable并最终绑定到Grid。



SqlDataReader dr = cmd.ExecuteReader（CommandBehavior.CloseConnection）;

DataTable dt = new DataTable（）;

dt.Load（dr）;

public partial class登录：表格

{

SqlConnection con = new SqlConnection（@ Data Source = .\SQLEXPRESS; Initial Catalog = Library_management_system; Integrated Security = True; User Instance = True）;

int count = 0;

public Login（ ）

{

InitializeComponent（）;

}



private void button1_Click （对象发送者，E ventArgs e）

{

SqlCommand cmd = con.CreateCommand（）;

cmd.CommandType = CommandType.Text;

cmd.CommandText =select * from Library_person where usernaem ='+ textBox1.Text +'and password ='+ textBox2.Text +';



cmd.ExecuteNonQuery（）;

DataTable dt = new DataTable（）;

SqlDataAdapter da = new SqlDataAdapter（cmd）;

da .Fill（dt）;

count = Convert.ToInt32（dt.Rows.Count.ToString（））;

if（count == 0）

{

MessageBox.Show（用户名密码不匹配）;

}

其他

$



this.Hide（）;

mdi_user mu = new mdi_user（）;

mu .Show（）;

}

}



private void Login_Load（object sender，EventArgs e）

{

if（con.State == ConnectionState.Open）

{

con.Close（）;

}

con.Open（）;



}

}

I'm having problem in executing non query sql statement. Bear in mind, I'm still new to .NET framework and MySQL. Here is my code.

private void Binding()
{
    string connStr = "datasource=localhost;port=3306;username=root;password=root;";
    conn = new MySqlConnection(connStr);
    MySqlCommand command = conn.CreateCommand();
    try
    {
        string database = schemaForm.getData;
        dtable = new DataTable();
        bindingSource = new BindingSource(); ;

            conn.Open();
            command.CommandText = "SELECT Metabolite_Name" +
                                  "FROM " + database +
                                  ".Metabolites WHERE"+
                                  " MetaboliteID IN ('met1', 'met2');";
            command.ExecuteNonQuery();
            sqlData.SelectCommand = command;
            sqlData.Fill(dtable);
            bindingSource.DataSource = dtable;
            dbMetName.DataSource = dtable;
            dtable.Columns.Add("Metabolite Name");
            dbMetName.DataSource = dtable;
            conn.Close();
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

Passing value from getData form

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace DynamicSimulator_v2
{
    public partial class SchemaName : Form
    {
        private static string data;
        public SchemaName()
        {
            InitializeComponent();
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Hide();
        }

        private void btnOK_Click(object sender, EventArgs e)
        {
            data=txtDB.Text;
            this.Hide();
        }

        public string getData
        {
            set
            {
                data = txtDB.Text;
            }
            get
            {
              return data;
            }
        }
    }
}

The error shows that my query is wrong. I pretty sure the query was right as I tested it on MySQL script. And I try to show it in datagridview by the way. dbMetName is datagridview.

解决方案

Quote:

command.ExecuteNonQuery();

is used for Insert/Update

You should be using ExecuteReader and load the data to DataTable and finally bind to Grid.

SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
DataTable dt = new DataTable();
dt.Load(dr);

public partial class Login : Form
{
SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=Library_management_system;Integrated Security=True;User Instance=True");
int count = 0;
public Login()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
SqlCommand cmd=con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "select * from Library_person where usernaem='"+textBox1.Text+"' and password='"+textBox2.Text+"'";

cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
count=Convert.ToInt32(dt.Rows.Count.ToString());
if(count==0)
{
MessageBox.Show("username password does not match");
}
else
{

this.Hide();
mdi_user mu = new mdi_user();
mu.Show();
}
}

private void Login_Load(object sender, EventArgs e)
{
if(con.State==ConnectionState.Open)
{
con.Close();
}
con.Open();

}
}

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