i have a problem with making a local database into my c# project and creating it..
I tried first with making a Microsoft Sql Server but the problem is that i need to make app which should run on every pc. The app should input data from user , and collect it to the database, and on every start of program, the database should be filled with the leftover of earlier input.. What you suggest me to do?
First to connect your c# application with sqlite you should start with getting connection string
private static string executableLocation = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
private static string oldconnectionstring = Path.Combine(executableLocation, "YourDB.db");
private static string connectionString = "Data Source =" + oldconnectionstring.ToString();
After getting connection, to add your input to database follow below steps
using (SQLiteConnection conn = new SQLiteConnection(connectionString))
{
//Open connection to DB
conn.Open();
//Query to be fired
string sql = "Your Query to insert rows";
//Executing the query
using (SQLiteCommand cmd = new SQLiteCommand(sql, conn))
{
//Executing the query
cmd.CommandText = sql;
cmd.ExecuteNonQuery();
}
//Close connection to DB
conn.Close();
}
Related
I'm trying to update a CLOB column in my database with a long string containing the HTML contents of an email. There are 18,000 characters in the record I'm having an issue with.
The below code will work if I set the html variable to "short string". But if I try to run the code with the long 18,000 character HTML string, I get this error: "Oracle.DataAccess.Client.OracleException ORA-22922: nonexistent LOB value ORA-02063: preceding line from ((servername))"
public static void UpdateHtmlClob(string html, string taxId,string un, string pw)
{
using (OracleConnection conn = new OracleConnection())
{
try
{
conn.ConnectionString = "User Id=" + un + ";Password=" + pw + ";Data Source=server.com;";
conn.Open();
OracleCommand cmd = new OracleCommand();
string indata = html;
cmd.CommandText = "UPDATE table1 SET HTML_BODY = :clobparam";
OracleParameter clobparam = new OracleParameter("clobparam", OracleDbType.Clob, indata.Length);
clobparam.Direction = ParameterDirection.Input;
clobparam.Value = indata;
cmd.Parameters.Add(clobparam);
cmd.Connection = conn;
cmd.ExecuteNonQuery();
conn.Close();
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
conn.Close();
}
}
}
Before you edited your code to reflect my answer, there were two problems with your code that I saw.
Firstly, you need to use a colon in your command text to tell Oracle that clobparam is a bind variable, not a column name:
cmd.CommandText = "UPDATE table1 SET HTML_BODY = :clobparam";
Secondly, you were not setting the database connection anywhere on the command. Which connection should the command be using? In your situation you have only one connection but more generally it may be possible to have more than one connection open. Add the line
cmd.Connection = connection;
or alternatively create the command using
OracleCommand cmd = connection.CreateCommand();
Of course, it would be nice if Oracle.DataAccess returned an error message that gave you the slightest hint that this was what you were doing wrong.
Anyway, now that you've edited your question to include the critical detail ORA-02063: preceding line from ((servername)), which tells us that you are using a database link, all I can really do is echo what I wrote in the comment: connect direct to the remote database to transfer LOB data, don't use a database link.
I am trying to rebuild an application that originally used sqlite to now use 'localdb'. (I want an application that can create its own database locally and at runtime without requiring a pre-installed instance of sql server or sql express on the target machine)
I want to move away from using a 'third party' library (sqlite) as experience has told me it can be a pain to get it working from scratch, and towards something supposedly more straightforward to get up and running from scratch.
Using code copied (and slightly modified) from the web I have managed to create an mdf file dynamically/programmatically, but I am puzzled by what happens if I run it more than once, even if I choose a new filename each time. Namely it seems to somehow keep the changes/additions made on each run. Below is the relevant code...
public partial class Form1 : Form
{
SqlConnection conn;
public void CreateSqlDatabase(string filename)
{
string databaseName =
System.IO.Path.GetFileNameWithoutExtension(filename);
conn = new SqlConnection(
String.Format(
#"Data Source=(LocalDB)\v11.0;Initial Catalog=master;Integrated Security=True"
));
conn.Open();
using (var command = conn.CreateCommand())
{
command.CommandText =
String.Format(
"CREATE DATABASE {0} ON PRIMARY (NAME={0}, FILENAME='{1}')"
, databaseName, filename);
command.ExecuteNonQuery();
command.CommandText =
String.Format("EXEC sp_detach_db '{0}', 'true'", databaseName);
command.ExecuteNonQuery();
}
conn.Close();
}
private void button1_Click(object sender, EventArgs e)
{
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
CreateSqlDatabase(openFileDialog1.FileName);
}
}
private void button2_Click(object sender, EventArgs e)
{
conn.Open();
SqlCommand comm = conn.CreateCommand();
comm.CommandText =
"create table mytable (id int, name nvarchar(100))";
comm.ExecuteNonQuery();
comm.CommandText =
"insert into mytable (id,name) values (10,'testing')";
comm.ExecuteNonQuery();
comm.CommandText = "select * from mytable";
SqlDataReader reader = comm.ExecuteReader();
while (reader.Read())
{
textBox1.Text +=
reader["id"].ToString() + ", " + reader["name"].ToString() + "\r\n";
}
conn.Close();
}
}
If I run the app once It runs through fine.
If I run the app a second time, and choose a different filename for the database it tells me 'mytable' already exists.
If I comment out the create table code it runs, but the select query returns multiple rows indicating multiple inserts (one for each time the app runs)
I am just seeking to understand why this happens. Do I need to delete database/table each time if I want the app to behave as if it has created the database/table from scratch on each subsequent run?
You have initial catalog 'master' in your connection string. Are you sure you haven't created the tables in the master database instead of the newly created database?
After the creation & detach of the database file, you could try and change your connection to:
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\v11.0;Integrated Security=True;AttachDbFilename=c:\xxx\xxx\xxx.mdf");
Im simply just trying to read what there is in the batabase on to a console but i always get an exception on the conn.Open() line. Here is all the code:
SqlConnectionStringBuilder conn_string = new SqlConnectionStringBuilder();
conn_string.DataSource = "mysql14.000webhost.com"; // Server
conn_string.UserID = "a7709578_codecal";
conn_string.Password = "xxxxx";
conn_string.InitialCatalog = "a7709578_codecal"; // Database name
SqlConnection conn = new SqlConnection(conn_string.ToString());
conn.Open();
SqlCommand cmd = new SqlCommand("Select name FROM Users");
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Console.WriteLine("{1}, {0}", reader.GetString(0), reader.GetString(1));
}
reader.Close();
conn.Close();
if (Debugger.IsAttached)
{
Console.ReadLine();
}
You need to build the connection string manually or use MySqlConnectionStringBuilder. MySql uses a different format than SQL Server and the SqlConnectionStringBuilder that you're using. You also need to use a MySQL library, SqlConnection, SqlCommand, etc are all build specifically for SQL Server.
MySQL connectors
For MySQL database you are using wrong provider. Those classes you have used in posted code are for SQL Server. Your code should look like below with MySQL provider related classes
MySqlConnectionStringBuilder conn_string = new MySqlConnectionStringBuilder();
conn_string.Server = "mysql14.000webhost.com";
conn_string.UserID = "a7709578_codecal";
conn_string.Password = "xxxxxxx";
conn_string.Database = "a7709578_codecal";
using (MySqlConnection conn = new MySqlConnection(conn_string.ToString()))
Check Related post in SO
Also to point out, you are selecting only one column from your table as can be seen
new SqlCommand("Select name FROM Users");
Whereas trying to retrieve two column value, which is not correct
Console.WriteLine("{1}, {0}", reader.GetString(0), reader.GetString(1))
000webhost free servers does not allow external connections to the server database.
You can only use your database from your PHP scripts stored on the server.
You can get data from database using PHP and it will return.So i advice to you using php from C# like api.
I'm creating a system using SQL Server 2012 for database, but when this system is starting first time in a computer, I want the system create the database and tables for me no create this manual.
How to I create database with C#? And how to I set connect string? because normally I set database name in the connect string, but now, I need create database before
You can use SQL script, leave database name empty. Example code here :
static void Main(string[] args)
{
using (var conn = new SqlConnection("data source=DBServer; uid=UserName; pwd=Password;"))
{
using (var cmd = new SqlCommand())
{
conn.Open();
cmd.Connection = conn;
cmd.CommandText = "Create Database NewDB;";
cmd.ExecuteNonQuery();
cmd.CommandText = "Use NewDB;CREATE TABLE dbo.Table1 (ID int, Data nvarchar(128));";
cmd.ExecuteNonQuery();
}
}
}
I want to get into developing applications that use databases. I am fairly experienced (as an amateur) at web based database utilization (mysql, pdo, mssql with php and old style asp) so my SQL knowledge is fairly good.
Things I have done already..
Create forms application
Add four text boxes (first name, last name, email, phone)
Added a datagrid control
Created a database connection using 'Microsoft SQL Server Database File (SqlClient)'
Created a table with fields corresponding to the four text boxes.
What I want to be able to do now is, when a button is clicked, the contents of the four edit boxes are inserted using SQL. I don't want to use any 'wrapper' code that hides the SQL from me. I want to use my experience with SQL as much as possible.
So I guess what I am asking is how do I now write the necessary code to run an SQL query to insert that data. I don't need to know the SQL code obviously, just the c# code to use the 'local database file' connection to run the SQL query.
An aside question might be - is there a better/simpler way of doing this than using the 'Microsoft SQL Server Database File' connection type (I have used it because it looks like it's a way to do it without having to set up an entire sql server)
The below is inserting data using parameters which I believe is a better approach:
var insertSQL = "INSERT INTO yourTable (firstName, lastName, email, phone) VALUES (firstName, lastName, email, phone)";
string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI; User ID=userid;Password=pwd;"
using (var cn = new SqlCeConnection(connectionString))
using (var cmd = new SqlCeCommand(insertSQL, cn))
{
cn.Open();
cmd.Parameters.Add("firstName", SqlDbType.NVarChar);
cmd.Parameters.Add("lastName", SqlDbType.NVarChar);
cmd.Parameters.Add("email", SqlDbType.NVarChar);
cmd.Parameters.Add("phone", SqlDbType.NVarChar);
cmd.Parameters["firstName"].Value = firstName;
cmd.Parameters["lastName"].Value = lastName;
cmd.Parameters["email"].Value = email;
cmd.Parameters["phone"].Value = phone;
cmd.ExecuteNonQuery();
}
This is selecting data from database and populating datagridview:
var dt = new DataTable();
string connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI; User ID=userid;Password=pwd;"
using (var cn = new SqlCeConnection(connectionString )
using (var cmd = new SqlCeCommand("Select * From yourTable", cn))
{
cn.Open();
using (var reader = cmd.ExecuteReader())
{
dt.Load(reader);
//resize the DataGridView columns to fit the newly loaded content.
yourDataGridView.AutoSize = true; yourDataGridView.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.AllCells);
//bind the data to the grid
yourDataGridView.DataSource = dt;
}
}
This first example is an over view based upon how I think it will be easier to understand but this is not a recommended approach due to vulnerability to SQL injection (a better approach further down). However, I feel it is easier to understand.
private void InsertToSql(string wordToInsert)
{
string connectionString = Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI; User ID=myDomain\myUsername;Password=myPassword;
string queryString = "INSERT INTO table_name (column1) VALUES (" + wordToInsert + ")"; //update as you feel fit of course for insert/update etc
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open()
SqlDataAdapter adapter = new SqlDataAdapter();
SqlCommand command = new SqlCommand(queryString, connection);
command.ExecuteNonQuery();
connection.Close();
}
}
I would also suggest wrapping it in a try/catch block to ensure the connection closes if it errors.
I am not able to test this but I think it is OK!
Again don't do the above in live as it allows SQL injection - use parameters instead. However, it may be argued it is easier to do the above if you come from PHP background (just to get comfortable).
This uses parameters:
public void Insert(string customerName)
{
try
{
string connectionString = Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI; User ID=myDomain\myUsername;Password=myPassword;
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
connection.Open() SqlCommand command = new SqlCommand( "INSERT INTO Customers (CustomerName" + "VALUES (#Name)", connection);
command.Parameters.Add("#Name", SqlDbType.NChar, 50, " + customerName +");
command.ExecuteNonQuery();
connection.Close();
}
catch()
{
//Logic in here
}
finally()
{
if(con.State == ConnectionState.Open)
{
connection.Close();
}
}
}
And then you just change the SQL string to select or add!