I have a c# winform project that supposes to save data to SQLite database, I've already used the dll properly and it runs without error, but I get an exception when trigger the method with buttonClick event
here the exception i got : Keyword not supported :'version'.
this the connection string:
"Data Source = Diary.db;Version = 3;New = False;Compress = True;";
and this the complete method :
private void AddToDbaseSQL3()
{
try{
string query = "insert into Diary(title,date,mood,wheater,content)
values('"+TitleTextbox.Text+"','"
+dateTimePicker.Value.Date.ToString("yyyy-MM-dd HH:mm")+"','"
+MoodCombobox.SelectedItem+"','"
+WheaterCombobox.SelectedItem+"','"
+ContentTextbox.Text+"');";;
SqlConnection connect2 = new SqlConnection(connection2);
SqlCommand cmd = new SqlCommand(query,connect2);
SqlDataReader read;
connect2.Open();
read = cmd.ExecuteReader();
while(read.Read())
{
}
MessageBox.Show("created");
TitleTextbox.Text = "Title";
TitleTextbox.ForeColor = SystemColors.ControlLight;
ContentTextbox.Clear();
connect2.Close();
}catch(Exception e){
MessageBox.Show(e.Message);
}
}
I've looked to this link:
Keyword not supported: 'version'
and it said to change SqlConnection to SQLiteConnection but it ended with an error, can you tell what's is the right connection string ? or there is something wrong from my code/method? please tell me, thank you, I'm sorry because it's my first time using the SQLite
SqlConnection from System.Data.SqlClient is for SQL Server.
You need an dedicated SQLite ADO.NET provider.
You can found the System.Data.SQLite provider from SQLite team here:
https://system.data.sqlite.org
Or you can use any libre or commercial provider.
You can also use the free and open-source SQLite ODBC driver that works fine and allow to use VS Visual Designers to create strongly typed ADO.NET DataSets, in addition to the use of OdbcConnection, OdbcCommand and so on:
http://www.ch-werner.de/sqliteodbc
C# Reading data from existing SQLite database
Related
I am using visual studio Windows forms for a login/sign-up project. So how would I go about connecting my Microsoft access data base to my visual studio project and establishing a connection in the code so I can write out a command.
It uses a connection string similar to SQL.
public string ConnString => $"Provider=Microsoft.ACE.OLEDB.16.0;Data Source = {FilePathHere};"
To persist to the file using ADO.NET, it will look like
private void ExecuteWrite(string sql)
{
try
{
using (OleDbConnection conn = new OleDbConnection(ConnString))
{
OleDbCommand cmd = new OleDbCommand(sql, conn) { CommandType = CommandType.Text };
conn.Open();
_ = cmd.ExecuteNonQuery();
}
}
catch (Exception e)
{
MessageBox.Show(e.Message);
Console.WriteLine(e.ToString());
}
}
A couple notes on Access:
Access has its own form of SQL which is very different than what you are used to, for example instead of char varchar you will have types like text. Check the full list of differences here
the SQL string you write must use " to escape things such as problematic column names
Tables cannot exceed 255 columns for some reason. Be ready to create seperate queries to split any massive table that goes over that limit, as Access will straight up refuse to process that query. Its the only db I know that suffers from such a limitation and it was a pain for a project I worked on. I got around it using some LINQ to split up the desired columns, and then crafting the separate CREATE or INSERT queries
I am using this code but getting an error of 'Object reference not set to an instance of an object.' at con.open() ? what am I doing wrong ?
I have already download and installed ODAC component version 10 , 11 ,12 trying each one at the failure of the latest one but still same error
using Oracle.DataAccess.Client;
namespace WindowsFormsApplication1
{
class OraTest
{
public OracleConnection con = new OracleConnection();
public void Connect()
{
con.ConnectionString = "Data Source=(DESCRIPTION= (ADDRESS = (PROTOCOL = TCP)(HOST =myip) (PORT = myport))(CONNECT_DATA = (SERVER = dedicated)(SERVICE_NAME = mydb)));User ID=myid;Password=mypass;";
con.Open(); //error here
}
public void Close()
{
con.Close();
con.Dispose();
}
}
Please go through this link
Getting Started with Oracle Data Provider for .NET (C# Version)
http://www.oracle.com/webfolder/technetwork/tutorials/obe/db/dotnet/GettingStartedNETVersion/GettingStartedNETVersion.htm
If you add a try/catch block in Connect(), you'll be able to catch the error.
For example:
When opening an oracle connection, connection object is null
I added the try catch block, and it returned ORA12154 - TNS could not
be resolved. After some research, I added an SID to my tnsnames.ora
file in my ODP for .NET Oracle home path, and it worked
See also Troubleshooting Oracle Net Services for troubleshooting possible connection issues from Oracle clients (such as your C# program).
But your first step is absolutely to determine the Oracle-level error (for example, ORA-12543 (could not connect to server host) or TNS-12514 (could not find service name)
MSDN: OracleException Class
public void ShowOracleException()
{
OracleConnection myConnection =
new OracleConnection("Data Source=Oracle8i;Integrated Security=yes");
try
{
myConnection.Open();
}
catch (OracleException e)
{
string errorMessage = "Code: " + e.Code + "\n" +
"Message: " + e.Message;
System.Diagnostics.EventLog log = new System.Diagnostics.EventLog();
log.Source = "My Application";
log.WriteEntry(errorMessage);
Console.WriteLine("An exception occurred. Please contact your system administrator.");
}
}
It's significant that con.ConnectionString = xyz works, but the following `con.Open()" fails. This means .Net is creating the C# object, but Oracle/TNS is failing when you try to use it.
ADDITIONAL SUGGESTIONS:
Re-read
When opening an oracle connection, connection object is null.
Read all of the suggestions, including the one about "Data Source in your connection string".
Focus on your connection string. It couldn't hurt to specify the connection string in your OracleConnection() constructor, if possible. Here's another link:
ODP.NET Connection exception
It would be great if you can verify connectivity from your PC with some other Oracle client, besides your C#/.Net program. To verify you're talking to the right TNS host and service, with the correct username/password. For example, maybe you have SQLDeveloper or sqlplus.
Finally, re-read the TNS troubleshooting link:
https://docs.oracle.com/cd/E11882_01/network.112/e41945/trouble.htm#NETAG016
What worked for me with the same error was to simply switch from the 'plain' Oracle DataAccess library, to the 'Managed' version.
This is an extemely easy change to make -
Add a Reference in your c# project to the Oracle.ManagedDataAccess library
Replace the existing use statements at the top of your Oracle client code with the following:
using Oracle.ManagedDataAccess.Client;
using Oracle.ManagedDataAccess.Types;
Include the Oracle.ManagedDataAccess.dll file with your exe
I am developing a WPF application.
I created a local SQLite database (using System.Data.SQLite):
SQLiteConnection conn = new SQLiteConnection("Data Source=test.db");
And need to fill it with a MySQL database located in a server. I already got to download the .sql dump file from the server, the problem is that how can i import this file to my local database?
I already searched on the web and found this question the problem is that this mention android...
Any information is welcome.
UPDATE 1:
Opening the .sql file and executing a SQLite command does not import the .sql, here is my code:
string lines = "";
try
{
using (StreamReader sr = new StreamReader(databaseFile))
{
lines += sr.ReadToEnd();
}
} catch (Exception)
{
}
SQLiteConnection conn = new SQLiteConnection("Data Source=test.db");
conn.Open();
var command = conn.CreateCommand();
command.CommandText = lines;
command.ExecuteNonQuery();
conn.Close();
The application crashes with the next error:
Additional information: SQL logic error or missing database
near "AUTO_INCREMENT": syntax error
They are different SQL dialects so that solution is going to give you quite a bit of a headache.
If this is a one time activity I would use a (free) tool like:
http://www.sql-workbench.net/
that has a Data Pump tool that allows you to move data across different databases.
I just started working on a sample application that only calls some tables on my SQLite database, and I have managed to solve other issues that have happened except this one.
Although I have searched for this, none of the suggested solutions for the connectionstring, permission issues and etc seem to be valid and working for me. For the permissions, I added the Everyone user with full control, and I still get the same error.
Below is the code that I am trying to execute:
// calling function
void getRecords2()
{
MySqlLite.DataClass ss = new MySqlLite.DataClass();
DataTable dt = ss.selectQuery("select * from english_words");
}
// the SQLite class that execute the code
using System.Data;
using System.Data.SQLite;
namespace MySqlLite
{
class DataClass
{
private SQLiteConnection sqlite;
public DataClass()
{
//This part killed me in the beginning. I was specifying "DataSource"
//instead of "Data Source"
sqlite = new SQLiteConnection(#"Data Source=C:\testwork\db\MrPick.sqlite3.db;Version=3;FailIfMissing=True");
}
public DataTable selectQuery(string query)
{
SQLiteDataAdapter ad;
DataTable dt = new DataTable();
try
{
SQLiteCommand cmd;
sqlite.Open(); //Initiate connection to the db
cmd = sqlite.CreateCommand();
cmd.CommandText = query; //set the passed query
ad = new SQLiteDataAdapter(cmd);
ad.Fill(dt); //fill the datasource
cmd.Dispose();
sqlite.Dispose();
}
catch (SQLiteException ex)
{
//Add your exception code here.
}
sqlite.Close();
return dt;
}
}
}
Note: I used the following assembly:
ADO.NET SQLite Data Provider
Version 1.0.82.0 September 3, 2012
Using SQLite 3.7.14
Originally written by Robert Simpson
Released to the public domain, use at your own risk!
Official provider website: http://system.data.sqlite.org/
I really appreciate your help on this.
Per your comment, you're getting a "Unable to open database file" error because you're pointing the code at a file that doesn't exist.
A "Table not found" error means it found the database, but not the table you were looking for. On the other hand, "Unable to open database file" means that it couldn't even find the database, and didn't even bother looking for a table. You're much closer to it working correctly when you're getting "Table not found".
You should change the path back to match the file on disk, then use a tool like the Firefox SQLite Manager to confirm that the english_words table does exist in your database.
If it doesn't, you should create it with that tool, and if it does, you should post another question here about the "Table not found" error.
Hopefully that helps.
When I ran into this error I had to set parseViaFramework in the SQLiteConnection constructor to true.
SQLiteConnection connection = new SQLiteConnection(connectionString, true);
connection.Open();
I was facing same issue on the shared hosting server,
My C# code was able to read data from SQLIte db file.
But while add / update data it was throwing Error "unable to open database"
I tried many options suggested on stackoverflow
But after referring
https://stackoverflow.com/a/17780808/2021073
and
https://www.sqlite.org/pragma.html#pragma_journal_mode
I tried adding journal mode=Off; to the Connection string
and it worked for me
sample code
SQLiteConnection connection = new SQLiteConnection("Data Source=G:\dbfolder\sqlite3.db;Version=3;Mode=ReadWrite;journal mode=Off;", true);
I am new to oracle and am trying to simply connect to an oracle db, but I am not sure where to find the proper credentials to put in the connection string. I simply downloaded and install oracle express edition on my machine, then installed the .Net references. My simple code is here:
string oradb = "Data Source=XE;User Id=hr;Password=hr;";
OracleConnection conn = new OracleConnection(oradb); // C#
try
{
conn.Open();
string sql = "SELECT FIRST_NAME FROM EMPLOYEES WHERE EMAIL='SKING'"; // C#
OracleCommand cmd = new OracleCommand(sql, conn);
cmd.CommandType = CommandType.Text;
OracleDataReader dr = cmd.ExecuteReader(); // C#
dr.Read();
//label1.Text = dr["dname"].ToString(); // C# retrieve by column name
label1.Text = dr.GetString(0).ToString(); // return a .NET data type
//label1.Text = dr.GetOracleString(0).ToString(); // return an Oracle data type
}
catch (OracleException ex)
{
label1.Text = ex.Message;
}
finally
{
conn.Close();
}
I am getting a TNS:could not resolve the connect identifier specified exception. Its probably because my connection string is wrong is what I am guessing. I cannot even go to the Server Explorer dialog in Visual Studio and test a connection correctly to my oracle db.
What steps do I need to take to figure out the proper credentials to plug into my connection string?
Or wording it like this....
If you were going to install oracle express on your machine, then connect to a .Net app what steps would you take to set up the connection string?
Maybe it is looking for a data source defined in a tnsnames.ora file called XE.
Try the Easy Connect naming method in the Express edition. It enables application clients to connect to a database without using any configuration files, simply by specifying the data source attribute through syntax shown below:
user id=hr;password=hr;data source=hr-server
user id=hr;password=hr;data source=hr-server:1521
user id=hr;password=hr;data source=hr-server:1521/XE
Replace hr-server with the dns name or ip of your machine.