I have the following code, but I can't seem to manipulate it to work the way I want. I would like to have the command search the data base for the first entry in the database that matches textbox2.text and delete the row.
private void button4_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\DillPickle\Documents\Data.mdf;Integrated Security=True;Connect Timeout=30");
SqlDataAdapter sda = new SqlDataAdapter("Select Count(*) From ACCNT where ACCNTNUM=" + textBox2.Text , con);
DataTable dt = new DataTable();
sda.Fill(dt);
if (dt.Rows[0][0].ToString() == "1")
{
ACCNT."txtbox2.text".Rows[0].Delete();
}
else
{
MessageBox.Show("The account does not exist in the record!");
}
}
There's many ways to accomplish what you are trying to do; here's one way:
private readonly string SqlConnectionString = #"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\DillPickle\Documents\Data.mdf;Integrated Security=True;Connect Timeout=30";
private readonly string SqlDeleteQuery = "DELETE FROM ACCNT WHERE ACCNTNUM=#accountNumber";
private void button4_Click(object sender, EventArgs e)
{
try
{
using (var sqlConnection = new SqlConnection(SqlConnectionString))
using (var sqlCommand = sqlConnection.CreateCommand())
{
sqlConnection.Open();
sqlCommand.CommandText = SqlDeleteQuery;
sqlCommand.Parameters.AddWithValue("#accountNumber", textBox2.Text);
sqlCommand.ExecuteNonQuery();
}
}
catch (Exception ex)
{
// Do something with the exception, like log it...
}
}
Related
I have the following code:
SqlCommand writeCommand = new SqlCommand("INSERT INTO computers(id)VALUES()", conn.GetConnection());
writeCommand.ExecuteNonQuery();
The table computers contains an INT idientity(1,1) column named id.
When I run the code, I get a System.Data.SqlClient.SqlException: Incorrect syntax near ')'. I've tried to find a solution, but can't find one on the internet.
If the table has other columns as well, and you want to populate them with NULL or their DEFAULT values, then you can use DEFAULT VALUES:
INSERT INTO dbo.computers
DEFAULT VALUES;
If, however, your table only have the one column, then personally using an IDENTITY is the wrong choice; a table that just has an IDENTITY is clearly being misused. Instead, use a SEQUENCE:
CREATE SEQUENCE dbo.Computers START WITH 1 INCREMENT BY 1;
This scales far better, and doesn't suffer the likely race conditions you have. Then, when running an INSERT (or similar) you would use NEXT VALUE FOR dbo.Computers.
For an auto-incrementing identity column the database handles the id value unless I missed something in what you are attempting to do.
public void DemoInsert(string ComputerName, ref int newIdentifier)
{
using (var conn = new SqlConnection { ConnectionString = ConnectionString })
{
using (var cmd = new SqlCommand { Connection = conn })
{
cmd.CommandText = "INSERT INTO computers (ComputerName) " +
"VALUES (#ComputerName); " +
"SELECT CAST(scope_identity() AS int);";
cmd.Parameters.AddWithValue("#ComputerName", ComputerName);
cn.Open();
newIdentifier = (int)cmd.ExecuteScalar();
}
}
}
I have similar code like your app, think about it simple crud app
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
SqlConnection con;
SqlDataAdapter da;
SqlCommand cmd;
DataSet ds;
void fillGrid()
{
con = new SqlConnection("Data Source=.;Initial Catalog=schoolDb;Integrated Security=True");
da = new SqlDataAdapter("Select * from ogrenciler",con);
ds = new DataSet();
con.Open();
da.Fill(ds, "students");
dataGridView1.DataSource = ds.Tables["students"];
con.Close();
}
private void Form1_Load(object sender, EventArgs e)
{
fillGrid();
}
private void Addbtn_Click(object sender, EventArgs e)
{
cmd = new SqlCommand();
con.Open();
cmd.Connection = con;
cmd.CommandText="insert into students(StudentId,StudentName,StudentSurname,City) values("+StudentId.Text+",'"+StudentName.Text+"','"+StudentSurname.Text+"','"+City.Text+"')";
cmd.ExecuteNonQuery();
con.Close();
fillGrid();
}
private void Updatebtn_Click(object sender, EventArgs e)
{
cmd = new SqlCommand();
con.Open();
cmd.Connection = con;
cmd.CommandText = "update Students set ogrenci_ad='"+StudentName.Text+"',StudentName='"+StudentSurname.Text+"',City='"+City.Text+"' where StudentId="+StudentId.Text+"";
cmd.ExecuteNonQuery();
con.Close();
fillGrid();
}
private void Deletebtn_Click(object sender, EventArgs e)
{
cmd = new SqlCommand();
con.Open();
cmd.Connection = con;
cmd.CommandText = "delete from ogrenciler where ogrenci_no="+StudentId.Text+"";
cmd.ExecuteNonQuery();
con.Close();
fillGrid();
}
}
}
I'm trying to fill a datagridview with SQL Server table data and I get an error:
ExecuteReader: Connection property has not been initialized.
How do I fix this ?
private void BlackListLoad()
{
DataTable dt = new DataTable();
SqlCommand cmd = new SqlCommand();
BindingSource bs = new BindingSource();
var table = dt;
var connection =
#"Data Source=someone-someone\SQLEXPRESS;Initial Catalog=test;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
using (var con = new SqlConnection { ConnectionString = connection })
{
if (con.State == ConnectionState.Closed)
{
con.Open();
}
try
{
cmd.CommandText = #"SELECT * FROM [dbo].[Blacklist1]";
table.Load(cmd.ExecuteReader());
bs.DataSource = table;
ListGrid.ReadOnly = true;
ListGrid.DataSource = bs;
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message + " sql query error.");
}
}
}
You haven't given your SqlCommand a connection! As it states you need to do this. You can fix this by doing:
cmd.Connection = con; just before you execute the reader.
Read here for more information: https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.connection(v=vs.110).aspx
It also looks like you're not opening your connection, which can be fixed with:
con.Open();
With a new connection object, you do not need to check whether it's open, because it won't be.
Try it this way.
using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string connectionString = "Data Source=.;Initial Catalog=pubs;Integrated Security=True";
string sql = "SELECT * FROM Authors";
SqlConnection connection = new SqlConnection(connectionString);
SqlDataAdapter dataadapter = new SqlDataAdapter(sql, connection);
DataSet ds = new DataSet();
connection.Open();
dataadapter.Fill(ds, "Authors_table");
connection.Close();
dataGridView1.DataSource = ds;
dataGridView1.DataMember = "Authors_table";
}
}
}
I am trying to read my tables that are contained within my database in SQL Server Express, but it keeps coming up empty. What is it that am doing wrong?
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
string query = "SELECT * FROM INFORMATION_SCHEMA.TABLES";
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand command = new SqlCommand(query, connection);
command.Connection.Open();
command.ExecuteNonQuery();
}
}
Updated but still empty:
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
try {
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
SqlConnection con2 = new SqlConnection(connectionString);
con2.Open();
string query = "SELECT * FROM INFORMATION_SCHEMA.TABLES";
SqlCommand cmd2 = new SqlCommand(query, con2);
SqlDataReader dr2 = cmd2.ExecuteReader();
while (dr2.Read())
{
comboBox1.Items.Add((string)dr2[0]);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}}
Latest Updated code. Think I figured it but still showing empty:
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
try {
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
SqlConnection con2 = new SqlConnection(connectionString);
con2.Open();
string query = "SELECT * FROM INFORMATION_SCHEMA.TABLES ";
SqlCommand cmd2 = new SqlCommand(query, con2);
SqlDataReader dr2 = cmd2.ExecuteReader();
while (dr2.Read())
{
string Dtables = dr2.GetString(dr2.GetOrdinal("TABLE_NAME"));
comboBox1.Items.Add(Dtables);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}}
Full class:
namespace unique_database{ public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
}
private void button2_Click(object sender, EventArgs e)
{
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
string query = "CREATE TABLE [dbo].[" + textBox1.Text + "](" + "[Code] [varchar] (13) NOT NULL," +
"[Description] [varchar] (50) NOT NULL," + "[NDC] [varchar] (50) NULL," +
"[Supplier Code] [varchar] (38) NULL," + "[UOM] [varchar] (8) NULL," + "[Size] [varchar] (8) NULL,)";
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand command = new SqlCommand(query, connection);
command.Connection.Open();
command.ExecuteNonQuery();
}
SqlConnection con = new SqlConnection("Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True");
string filepath = textBox2.Text; //"C:\\Users\\jdavis\\Desktop\\CRF_105402_New Port Maria Rx.csv";
StreamReader sr = new StreamReader(filepath);
string line = sr.ReadLine();
string[] value = line.Split(',');
DataTable dt = new DataTable();
DataRow row;
foreach (string dc in value)
{
dt.Columns.Add(new DataColumn(dc));
}
while (!sr.EndOfStream)
{
value = sr.ReadLine().Split(',');
if (value.Length == dt.Columns.Count)
{
row = dt.NewRow();
row.ItemArray = value;
dt.Rows.Add(row);
}
}
SqlBulkCopy bc = new SqlBulkCopy(con.ConnectionString, SqlBulkCopyOptions.TableLock);
bc.DestinationTableName = textBox1.Text;
bc.BatchSize = dt.Rows.Count;
con.Open();
bc.WriteToServer(dt);
bc.Close();
con.Close();
}
private void button3_Click(object sender, EventArgs e)
{
OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.Filter = "CSV files (*.csv)|*.csv|XML files (*.xml)|*.xml";
if (openFileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
this.textBox2.Text = openFileDialog.FileName;
}
}
private void FillCombo()
{
try
{
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
using (SqlConnection con2 = new SqlConnection(connectionString))
{
con2.Open();
string query = "SELECT * FROM INFORMATION_SCHEMA.TABLES ";
SqlCommand cmd2 = new SqlCommand(query, con2);
SqlDataReader dr2 = cmd2.ExecuteReader();
while (dr2.Read())
{
int col = dr2.GetOrdinal("TABLE_NAME");
comboBox1.Items.Add(dr2[col].ToString());
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
Ok, first, don't use comboBox1_SelectedIndexChanged to fill comboBox1.
use YourForm.OnLoad event, the form constructor, or click a button, but don't use SelectedIndexChanged to fill itself, because you're executing this procedure every time you select one item of comboBox1.
To get column index simply use: dr2.GetOrdinal("TABLE_NAME");
private void FillCombo()
{
try
{
string connectionString = "Data Source=LPMSW09000012JD\\SQLEXPRESS;Initial Catalog=Pharmacies;Integrated Security=True";
using (SqlConnection con2 = new SqlConnection(connectionString))
{
con2.Open();
string query = "SELECT * FROM INFORMATION_SCHEMA.TABLES";
SqlCommand cmd2 = new SqlCommand(query, con2);
SqlDataReader dr2 = cmd2.ExecuteReader();
while (dr2.Read())
{
int col = dr2.GetOrdinal("TABLE_NAME");
comboBox1.Items.Add(dr2[col].ToString());
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
Use ExecuteReader() instead of ExecuteNonQuery().then Use SqlDataReader() for get result.
I wanted to populate data table with the value taken from the database. I want to use Select condition with the values taken from textbox.. I have written the following code in C#, please tell me whether it is a right approach. It is showing exception about connection string.. but I wanted to know whether my approach is correct or not.. please do comment.
public partial class searchsale : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
try
{
SqlConnection conn = new SqlConnection(#"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\rdb.mdf;Integrated Security=True;User Instance=True");
conn.Open();
string scriptname = TextBox1.Text;
string accnum = TextBox2.Text;
string sql = #"select scriptname,accnum,Quantity,price from transac where scriptname = #sn, accnum = #an and transactio = 'Sell'";
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = sql;
cmd.Parameters.AddWithValue("#an", accnum);
cmd.Parameters.AddWithValue("#sn", scriptname);
SqlDataReader dr = cmd.ExecuteReader();
DataTable dt = GetDataTable(sql);
}
catch (Exception ex)
{
Response.Write("error" + ex.ToString());
}
}
private DataTable GetDataTable (string sql)
{
DataTable dt = new DataTable();
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
{
SqlDataAdapter da = new SqlDataAdapter(sql, conn);
da.Fill(dt);
}
return dt;
}
}
The error with your code is because you have not set the connection property of your command .
and for using data table the most simple way is using :
try
{
var connection = #"your connection string";
//your command
var command = "your command";
var dataAdapter = new System.Data.SqlClient.SqlDataAdapter(command, connection);
var dataTable = new DataTable();
//Get data
dataAdapter.Fill(dataTable);
}
catch (System.Data.SqlClient.SqlException sqlEx)
{
//Use sqlEx.Number to hanlde excception more specific
//for example if sqlEx.Number -1 => Could Not Connect to Server.
}
catch (Exception ex)
{
}
Problem is in your below code line for GetDataTable (string sql) method. You will have to use ConnectionString property. I would suggest you to read about ADO.NET more from MSDN.
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
{
Should be
ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString
It should look like
using (SqlConnection conn = new
SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
your code looks right except the connection string. You have declared the connection string at the beginning as
SqlConnection conn = new SqlConnection(#"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\rdb.mdf;Integrated Security=True;User Instance=True");
But in your connection initialization it looks like you are getting it from App config file.
using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
So instead of having connection in your code put it in the app config file and remove the connection from your code
something like this
<?xml version="1.0"?>
<configuration>
<connectionStrings>
<add name="ConnectionString"
connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\rdb.mdf;Integrated Security=True;User Instance=True"/>
</connectionStrings>
</configuration>
Thank you,
Birhanu
public static class SqlDBHelper
{
public static DataSet ExecuteDataSet(string sql, CommandType cmdType, params SqlParameter[] parameters)
{
using (DataSet ds = new DataSet())
using (SqlConnection connStr = new SqlConnection(ConfigurationManager.ConnectionStrings["DbConn"].ConnectionString))
using (SqlCommand cmd = new SqlCommand(sql, connStr))
{
cmd.CommandType = cmdType;
foreach (var item in parameters)
{
cmd.Parameters.Add(item);
}
try
{
cmd.Connection.Open();
new SqlDataAdapter(cmd).Fill(ds);
}
catch (Exception ex)
{
throw ex;
}
return ds;
}
}
}
I'm having trouble updating data from a data grid view with the use of a button. The text is editable but the changes does not save to the SQLite database. any ideas?
private void ProjectsAdmin_Load(object sender, EventArgs e)
{
// TODO: This line of code loads data into the 'seniorProjectsDataSet2.DataTable1' table. You can move, or remove it, as needed.
this.dataTable1TableAdapter.Fill(this.seniorProjectsDataSet2.DataTable1);
}
private void dataGridView1_CellContentClick_1(object sender, DataGridViewCellEventArgs e)
{
if (e.RowIndex == -1 || e.ColumnIndex != 3) //ignore header row and any column that doesnt have file name
return;
var filename = dataGridView1.CurrentCell.Value.ToString();
if (File.Exists(filename))
Process.Start(filename);
}
private void updateData_Click(object sender, EventArgs e)
{
SQLiteConnection conn = new SQLiteConnection();
dataGridView1.EndEdit();
dataTable1TableAdapter.Adapter.Update(seniorProjectsDataSet.Tables[0]);
for (int i = 0; i < seniorProjectsDataSet.Tables[0].Rows.Count; i++)
{
seniorProjectsDataSet.Tables[0].Rows[i].AcceptChanges();
}
}
}
}
I solved the problem without a Button. In the following code I´ll give you a example how the connection and the update works with a mysql-database (update in runtime):
CODE
DataTable dt = null;
DataGridView dgv1 = null;
If the form load you have to set your dt variable to a new datatable:
private void Form1_Load(object sender, EventArgs e)
{
dt = new DataTable();
using (MySqlConnection conn = new MySqlConnection("datasource=localhost;port=3306;username=root;password=1234"))
{
conn.Open();
using (MySqlCommand cmd = new MySqlCommand())
{
cmd.Connection = conn;
cmd.CommandText = "select *from try.data ;";
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
da.Fill(dt);
}
conn.Close();
}
dgv1 = new DataGridView();
dgv1.AllowUserToAddRows = false;
dgv1.CellEndEdit += new DataGridViewCellEventHandler(dgv_CellEndEdit);
dgv1.CellValidating += new DataGridViewCellValidatingEventHandler(dgv_CellValidating);
dgv1.Dock = DockStyle.Fill;
dgv1.DataSource = dt;
this.Controls.Add(dgv1);
}
You have to set two events: CellValidating
private void dgv_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
InitializeComponent();
if (e.ColumnIndex == 0)
{
dgv1.CancelEdit();
}
}
and the CellValidating Event:
private void dgv_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
string id = dt.Rows[e.RowIndex]["Eid"] + "";
string col = dt.Columns[e.ColumnIndex].ColumnName;
string data = dgv1.Rows[e.RowIndex].Cells[e.ColumnIndex].Value + "";
string sql = string.Format("UPDATE `try`.`data` SET `{0}` = '{1}' WHERE Eid = {2};", col, data, id);
using (MySqlConnection conn = new MySqlConnection("datasource=localhost;port=3306;username=root;password=1234"))
{
conn.Open();
using (MySqlCommand cmd = new MySqlCommand())
{
cmd.Connection = conn;
cmd.CommandText = sql;
cmd.ExecuteNonQuery();
}
conn.Close();
}
}
This aktually works with MySql but in Sql are "Equal" components like the SqlConnection or the SqlCommand... I hope this solve you problem. Have a nice day!
using System.Data.SQLite;
SQLiteConnection con = new SQLiteConnection("Data Source=C:\\Cogs\\bin\\Release\\db\\my_database_file.db");
SQLiteCommand cmd = con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "select * from [my_table]";
con.Open();
cmd.ExecuteNonQuery();
DataTable dta = new DataTable();
SQLiteDataAdapter dataadp = new SQLiteDataAdapter(cmd);
dataadp.Fill(dta);
dataGridView1.DataSource = dta;
con.Close();