Develop Reference

Visual Studio Server Explorer show table data is blank

I am working on a Winforms c# program with a service-based database. I have created a table called Books which is empty and currently has no records.
Using some code, I am inserting into the table values. For some reason, when clicking Show Table Data, it still shows as blank despite me having added a record.
I checked to see if the record was there (but hidden) by using a DataGridView with the source of its data being the Books table. I could see the record had been created, but for some reason is not showing in the Server Explorer's Show Table Data view.
Here is my code for inserting a new record into the table:
string query = "INSERT INTO Books (ISBN, Title, Authors, Publishers, Genre, Page_Count, Quantity) VALUES (#isbn, #title, #authors, #publishers, #genre, #page_count, #quantity)";
string connectionString = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\LMSDB.mdf;Integrated Security=True";
// Establish connection with database
using (SqlConnection connection = new SqlConnection(connectionString))
{
// Avoid SQL injection using parameters. Replace them with their real values
SqlCommand command = new SqlCommand(query, connection);
command.Parameters.AddWithValue("#isbn", isbn);
command.Parameters.AddWithValue("#title", title);
command.Parameters.AddWithValue("#authors", authors);
command.Parameters.AddWithValue("#publishers", publishers);
command.Parameters.AddWithValue("#genre", genre);
command.Parameters.AddWithValue("#page_count", pageCount);
command.Parameters.AddWithValue("#quantity", quantity);
try
{
connection.Open();
if (command.ExecuteNonQuery() == 1)
{
// 1 Row affected. Success
Console.WriteLine("Book added to database successfully");
ClearControlValues();
}
}
catch (Exception ex)
{
MessageBox.Show("An error occured:\n" + ex.Message);
}
finally
{
connection.Close();
}
}
As you can see, the Show Table Data view is appearing blank, despite me knowing that there is a record as I can see it on a DataGridView
Is there something I'm missing as to why the record isn't appearing?
EDIT: Solved thanks to Steve who pointed out that the Server Explorer and my code had different connection strings. Having changed these around, I now have the intended result.

I made a test with your code, and data can be inserted successfully.
As Steve said, the problem lies in your connection string.
And you can find your connectionstring by following steps:
1.Right-click on the connection name and select Properties.
2.There is an item called Connection String in the Properties window.
As follows:
Daniel Zhang

C# fill an access database from a dataset

I have a program which is supposed to open, edit, create and save access databases. For saving I copy an empty database with just the tables (just to avoid going through the hassle of creating every table and column etc) and try to fill it with values via the TableAdapterManager.UpdateAll method.
string _TemplateConnectString = #"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};";
_connection = new OleDbConnection(string.Format(_TemplateConnectString, dlg.FileName));
_connection.Open();
DataSet1TableAdapters.TableAdapterManager tam=new TableAdapterManager();
tam.Connection = _connection;
try
{
tam.UpdateAll(dataset);
}
catch (System.Exception ex)
{
MessageBox.Show("Update failed");
}
It finishes with no exceptions but the values don't get inserted into the new database.
Also as far as I know the UpdateAll method only updates modified row so if I open some db and it inserts it's rows, it will not take them into account even though there are not in the database that I am trying to fill.
I have also tried filling the database with the ADODB and ADOX extensions but all the solutions I found with those was a lot of hardcoding and no regards for hierarchy, keys, etc.
Is there a way to force insert everything in the new database?

Is your template database in the Visual Studio project directory? It might have something to do with Visual Studio copying the database to the bin/debug or bin/release folder...

Try to use the right Data source database name, here an
example with an excel file:
cnn.Open "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=c:\somepath\ExcelFile.xls;" & _
"Extended Properties=""Excel 8.0;HDR=Yes;"";"

A clumsy solution but it works. I iterate the tables of the dataset and save the via an sql string generator like this:
void SaveTable(DataTable dt)
{
string[] inserts;
try
{
inserts = SqlHelper.GenerateInserts(dt, null, null, null);
foreach (string s in inserts)
{
OleDbCommand cmd = new OleDbCommand();
cmd.CommandText = s;
cmd.Connection = _connection;
int n = cmd.ExecuteNonQuery();
}
}
catch (Exception e)
{
SaveOk = false;
}
}
I found the SqlHelper somewhere on this site, but completely lost where, unforunately. So here is the pastebin with it https://pastebin.com/iCMVuYyu

I get no errors when adding a row to a DataTable, but the row is not added to the database

I am trying to add a row to a table in a PostgreSQL database using ODBC. Although no exceptions are thrown, the row is not being added to the table. Here is my code:
void TestNewRow()
{
try
{
DataSet dataSet = new DataSet();
OdbcDataAdapter adapter = new OdbcDataAdapter();
adapter.SelectCommand =
new OdbcCommand("select read_time from plant_genie.plc_values_by_tag", m_db.GetConnection());
OdbcCommandBuilder builder =
new OdbcCommandBuilder(adapter);
adapter.Fill(dataSet);
DataTable valuesTable = dataSet.Tables[0];
DataRow newRow = valuesTable.NewRow();
newRow["read_time"] = DateTime.Now;
valuesTable.Rows.Add(newRow);
valuesTable.AcceptChanges();
dataSet.AcceptChanges();
adapter.Update(dataSet);
}
catch (Exception ex)
{
int a = 1;
}
}
I have a breakpoint in the exception handler and another at the end of the function. The second breakpoint is hit but not the first, so no exception is being thrown. I have triple-checked that I'm connecting to the correct database. I don't think I should need two AcceptChanges() calls and an Update() call, but even with all of that overkill, I'm still not getting a new row in my table. What am I doing wrong?
I tried to find a duplicate of this question, but there are so many questions about adding rows that if there was a duplicate, it is being hidden.
Thank you for your help.
RobR

Calling AcceptChanges marks all changes as accepted (i.e. it resets the state of everything to Unmodified), so no changes will be saved to the database. Remove this call to both the table and dataset and your changes should be saved.

WPF/SQL - how to get tables from a selected database into a ListView

Good evening,
i'm at the beginning of an IT apprenticeship and i've started my own little project. I've got following problem:
I've created in WPF a standard Login Window for getting SQL Connection Datas. This Window is working fine and i only can switch to the next window when the entered Login-Datas are correct. My problem is the second window. In the second one i have one ListBox for listing every Database from the connected Server. Next to this ListBox i've a ListView. In this ListView i want to see the tables from the selected Database.
Code for listing Databases:
SqlConnection GetConnection = new SqlConnection("Server=admin-pc;user Id=sa;Password=123;");
try
{
this.libDatabase.Items.Clear();
DataTable databases = new DataTable("Databases");
using (IDbConnection connection = GetConnection)
{
IDbCommand command = connection.CreateCommand();
command.CommandText = "SELECT * FROM sys.Databases";
connection.Open();
databases.Load(command.ExecuteReader(CommandBehavior.CloseConnection));
}
this.libDatabase.Items.Clear();
foreach (DataRow row in databases.Rows)
this.libDatabase.Items.Add(row[0].ToString());
}
catch (SqlException)
{
this.libDatabase.Items.Clear();
this.libDatabase.Items.Add("Connection error");
}
catch (Exception ex)
{
MessageBox.Show("Error while loading available databases");
}
finally
{
GetConnection.Close();
}
libDatabase is the name of the ListBox.
This Code is working good and every Database is shown in my ListBox. But no i've a totally Blackout. How do i get the Tables from the selected Database into the ListView? I've tried the same way like i did with the Databases but with a different "SELECT"-Statement ==> "select * from {0}", listbox.SelectedItem
Here are different Codes i've tried but i think that i do something completely wrong.
First Version:
List<ListViewItem> gettables = new List<ListViewItem>();
if (libDatabase.SelectedItem != null)
{
SqlConnection con = new SqlConnection("Server=admin-pc;user Id=sa;Password=123;");
string strSQL = string.Format("select * from {0}", libDatabase.SelectedItem);
SqlCommand cmd = new SqlCommand(strSQL, con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
}
reader.Close();
con.Close();
}
Second Version:
SqlConnection GetConnection = new SqlConnection("Server=admin-pc;user Id=sa;Password=123;");
try
{
this.libTables.Items.Clear();
DataTable tables = new DataTable("Tables");
using (IDbConnection connection = GetConnection)
{
IDbCommand command = connection.CreateCommand();
if (libDatabase.SelectedItem != null)
{
command.CommandText = string.Format("SELECT * FROM {0}", libDatabase.SelectedItem);
connection.Open();
tables.Load(command.ExecuteReader());
}
}
this.libTables.Items.Clear();
foreach (DataRow row in tables.Rows)
this.libTables.Items.Add(row[0].ToString());
}
catch (SqlException)
{
this.libTables.Items.Clear();
this.libTables.Items.Add("Connection error. Check server");
}
catch (Exception ex)
{
MessageBox.Show("Error while loading available tables" + ex);
}
finally
{
GetConnection.Close();
}
libTables is the name of the ListView.
Maybe i did it completely wrong or there's just one code block false.
Thank you for supporting.
Dave S.

Try this select statement instead:
command.CommandText = string.Format("SELECT * FROM {0}.sys.tables", libDatabase.SelectedItem);
As the database names are to be found in sys.databases within master, so too the tables are to be found within sys.tables for each database.
It pays to step through code of this nature with a debugger, and/or put a breakpoint at each meaningful location. Verify each sql statement built in the code is exactly what you intended, and execute each statement within Sql Management studio using the same permissions under which it is being executed within your code, to ensure the statement will produce the results you want.
Edit for triggering the table load:
You must also ensure the table-loading process is triggered by the appropriate action. In this case, it would most likely need to be triggered by the user selecting a database within the database listbox. You'll need to add an event handler for the SelectionChanged event to the listbox. (Note that I'm assuming you're not using the MVVM pattern based on the code samples you included in your question.)
Add the SelectionChanged attribute to your ListBox definition:
<ListBox Name="libDatabase" SelectionChanged="libDatabase_SelectionChanged">
And in the codebehind, define the event handler:
private void libDatabase_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
{
if(libDatabase.SelectedItem != null)
{
// open a database connection and select your tables here.
}
}

C# Winforms control - DataGridView - Update Database

The programs I am using are WAMP server (and its mysql feature in particular) and MS Visual Studio 2010 and I am programming in C#
Basically, here is what I need and can currently do with my application.
I have several datagridview's throughout the project and the first is simple, it loads all data from a specific table in the database at the push of a button. I have another form which I can insert records and have somehow managed to make a delete function which asks the user for 2 fields (first name and last name) and then it places these into a query and carries out the command.
What do I need to do?
I need to be able to implement some way for the form to update the database. I have chosen to do this through a datagridview control so the user can see what they are editting whilst they edit it.
I have the following code which I have tried to update the database based on the data in the datagridview control.
string connString = "server=localhost;User Id=root;database=collegelist;";
MySqlConnection conn = new MySqlConnection(connString);
string selectSQL = "SELECT * FROM collegeemployee";
conn.Open();
MySqlDataAdapter da = new MySqlDataAdapter(selectSQL, conn);
MySqlCommandBuilder builder = new MySqlCommandBuilder(da);
DataTable table = new DataTable();
try
{
dgView2.Rows.RemoveAt(dgView2.CurrentRow.Index);
da.Update(table);
}
catch (Exception exceptionObj)
{
MessageBox.Show(exceptionObj.Message.ToString());
}
the problem with this code (listed in a method obviously) is that while the grid is able to be modified, it is unable to pass the data back to the database.

Instead of updating your database with the empty table what you should do is.
i.Get the datasource . like
ii. Update/synchronize the data source and data adapter
Here is the code it should work, if it doesn't please comment and tell me the problem.
string connString = "server=localhost;User Id=root;database=collegelist;";
MySqlConnection conn = new MySqlConnection(connString);
string selectSQL = "SELECT * FROM collegeemployee";
conn.Open();
MySqlDataAdapter da = new MySqlDataAdapter(selectSQL, conn);
MySqlCommandBuilder builder = new MySqlCommandBuilder(da);
BindingSource BindingSourceToUpdate = (BindingSource)dgView2.DataSource; // because direct casting to data table was failing in VS2o1o
try
{
dgView2.Rows.RemoveAt(dgView2.CurrentRow.Index);
da.Update((DataTable)BindingSourceToUpdate.DataSource);
}
catch(exception)
{
}
conn.close();