We Keep Coding

Missing column from access database in datagridview

I have an access database in a windows forms application which I use to populate datagridviews. However one of the columns never displays and when specified within the select statement it returns a "No value given for one or more required parameters"
Here is the current code
string select_Schedules = "SELECT * FROM Schedules";
conn = new OleDbConnection(constr);
conn.Open();
ds = new DataSet();
adap = new OleDbDataAdapter();
cmd = new OleDbCommand(select_Schedules, conn);
adap.SelectCommand = cmd;
adap.Fill(ds);
dataGridView1.DataSource = ds.Tables[0].DefaultView;
dataGridView2.DataSource = ds.Tables[0].DefaultView;
dataGridView3.DataSource = ds.Tables[0].DefaultView;
dataGridView4.DataSource = ds.Tables[0].DefaultView;
conn.Close();
The column is indeed contained within the table
This what the "SELECT * " query returns
as seen the Show_Date column is missing. When specified through
SELECT Show_Date FROM Schedules
it returns the error as previously mentioned.

As Steve pointed out I had an old connection string in this specific form. A simple mistake indeed.
I bet that you are not looking at the same database that you are querying. Check your connectionstring. Did you use DataDirectory shortcut? – Steve
So my problem has been solved. Thank you.

Data type mismatch in criteria expression - started only recently

I use Access database. This error wasn't occurring 30 minutes ago.
ERROR is:
Data type mismatch in criteria expression.
OleDbConnection con = new OleDbConnection(Utility.GetConnection());
con.Open();
OleDbCommand cmd2 = new OleDbCommand("INSERT INTO Temsilci(isin_adi,isin_tanimi,verildigi_tarih,teslim_tarihi,sorumlu_marka,sorumlu_ajans,revize,Temsilci_isverenid)
values (#isinadi,#isintanimi,#vertarih,#testarih,#smarka,#sajans,#revize,#temsid)", con);
cmd2.Parameters.Add("isintanimi", txtMarkaAdi.Text);
cmd2.Parameters.Add("isinadi", txtisAdi.Text);
cmd2.Parameters.Add("smarka", txtMarkaTemsilcisi.Text);
cmd2.Parameters.Add("sajans", txtAjansTemsilcisi.Text);
cmd2.Parameters.Add("revize", txtSorumluKisiler.Text);
cmd2.Parameters.Add("vertarih", txtverilisTarihi.Text);
cmd2.Parameters.Add("testarih", txtTeslimTarihi.Text);
cmd2.Parameters.Add("temsid", Session["UserID"]);
cmd2.ExecuteNonQuery();
con.Close();
My database columns are:
ID = AutoNumber
isin_adi = Short Text
isin_tanimi = Long Text
verildigi_tarih= Date/Time
teslim_tarihi=Date/Time
sorumlu_marka = Short Text
sorumlu_ajans=Short Text
personel_id=Number
revize=Short Text
is_durum=Short Text
Temsilci_isverenid=Number

I Solved the problem. I realized the rank of parameters was not true. i change my code like that:
OleDbConnection con = new OleDbConnection(Utility.GetConnection());
con.Open();
OleDbCommand cmd2 = new OleDbCommand("INSERT INTO Temsilci(isin_adi,isin_tanimi,verildigi_tarih,teslim_tarihi,sorumlu_marka,sorumlu_ajans,revize,Temsilci_isverenid) values (#isinadi,#isintanimi,#vertarih,#testarih,#smarka,#sajans,#revize,#temsid)", con);
cmd2.Parameters.Add("isinadi", txtisAdi.Text);
cmd2.Parameters.Add("isintanimi", txtMarkaAdi.Text);
cmd2.Parameters.Add("vertarih", txtverilisTarihi.Text);
cmd2.Parameters.Add("testarih", txtTeslimTarihi.Text);
cmd2.Parameters.Add("smarka", txtMarkaTemsilcisi.Text);
cmd2.Parameters.Add("sajans", txtAjansTemsilcisi.Text);
cmd2.Parameters.Add("revize", txtSorumluKisiler.Text);
cmd2.Parameters.Add("temsid", Session["UserID"]);
cmd2.ExecuteNonQuery();
con.Close();
after that i get error like this :
You cannot add or change a record because a related record is required in table 'Personel'.
And i remove the relationship from 2 tables. And now it works normally.
I think access database have some bugs ,and even if code is correct, errors may accuired.
So i will move my database to SQL from ACCESS i think. Thanks guys.

C# Fill combo box from SQL DataTable

DataTable _dt = new DataTable();
using (SqlConnection _cs = new SqlConnection("Data Source=COMNAME; Initial Catalog=DATABASE; Integrated Security=True"))
{
string _query = "SELECT * FROM Doctor";
SqlCommand _cmd = new SqlCommand(_query, _cs);
using (SqlDataAdapter _da = new SqlDataAdapter(_cmd))
{
_da.Fill(_dt);
}
}
cbDoctor.DataSource = _dt;
foreach(DataRow _dr in _dt.Rows)
{
cbDoctor.Items.Add(_dr["name"].ToString());
}
There was an Error...
The result is System.Data.DataRowView instead of data from database..

I'm not yet sure what is the exact error in your code, but if you're ok with not using DataTable, you can do it this way:
using (SqlConnection sqlConnection = new SqlConnection("connstring"))
{
SqlCommand sqlCmd = new SqlCommand("SELECT * FROM Doctor", sqlConnection);
sqlConnection.Open();
SqlDataReader sqlReader = sqlCmd.ExecuteReader();
while (sqlReader.Read())
{
cbDoctor.Items.Add(sqlReader["name"].ToString());
}
sqlReader.Close();
}
For more information take a look at SqlDataReader reference on MSDN.
In orer to find the issue in the original code you posted, please provide information in which line you get the exception (or is it an error that prevents application from compiling?) and what is its whole message.

You could also specify DisplayMember property of combobox to any of the column name.
For example if you want to display Name field, you could do
Combobox1.DisplayMember="Name";

I think the problem is that you are trying to insert multiple columns into a comboBox (which can accept only one column). Adjust your SELECT statement so that it combines all of the data you need into one column:
Example:
SELECT Name + ' ' LastName + ' '+ ID AS 'DoctorData' FROM Doctor
By using the + operator you can combine multiple columns from the database, and represent it as a single piece of data. I think that your code should work after that (you can even comment the foreach loop, I think that adding data source to your comboBox will be enough)

Determining if user login already exists in database?

I am building a web application in asp.net using C#. I have the Form where the user should register and then can login. I am having a problem in making the web app know that the name which the user picks is either "already exists" or not. If it already exists it should not insert the same name and display a message saying "user name already exists". I have tried the SqlDataReader but no luck.
protected void Register_Button_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["BJ_Player_String"].ToString());
SqlCommand cmd = new SqlCommand();
SqlCommand cmd2 = new SqlCommand();
SqlDataReader data_reader;
String name = TextBox2.Text;
String date = TextBox3.Text;
try
{
conn.Open();
cmd = new SqlCommand("Insert into BJ_Player (Player_Name, D_O_B) Values (#Player_name, #D_O_B)", conn);
cmd = new SqlCommand("Select Player_Name from BJ_Player WHERE Player_Name = #Player_name", conn);
cmd.Parameters.Add("#Player_name", SqlDbType.NVarChar).Value = name;
cmd.Parameters.Add("#D_O_B", SqlDbType.Date).Value = date;
cmd.Connection = conn;
data_reader = cmd.ExecuteReader();
cmd.ExecuteNonQuery();
if (data_reader.HasRows)
{
lblPlayerNameExists.Visible = true;
}
else
{
// do nothing
}
}

Make Player_Name unique in database then it will give you exception when you try to insert. You have to use unique constraint.
You have to give command type also and check you assigned both queries to same cmd object

in your code you're inserting data in your DB and then you are examining that the name is the same or not.
first you should search the name in your DB and then if there isn't any record with that name ,you should add your record.

I usually do it in one of two ways:
Create stored procedure that will check for name uniqueness and insert new record if everything is ok. It should return status as numeric code that you will check.
Check for name uniqueness before saving it using as a part of validation process.

Using the merge statement may help with this. Merge performs insert, update, or delete operations on a target table based on the results of a join with a source table.
Basically it inserts when needed, and updates when needed. Often times referred to as an upsert. but it gets the job done.
Here is a link to a site explaining how to use merge. Looks like a good article.
http://www.kodyaz.com/articles/sql-server-2008-t-sql-merge-statement-example.aspx

If you would like to write a model function to do that then
Leave it for ajax check which is pretty similar to the second
method
Issue "Select username from DB-table" to retrieve
usernames then check the username input against them before
displaying a view to report a problem if any or showing a message to
tell the user that "this name is valid", for example.

Problem with ADO.NET UPDATE code

Could somebody take a quick peek at my ado.net code? I am trying to update the row from a dataset, but it just isn't working. I am missing some elemental piece of the code, and it is just eluding me. I have verified that the DataRow actually has the correct data in it, so the row itself is accurate.
Many thanks in advance.
try
{
//basic ado.net objects
SqlDataAdapter dbAdapter = null;
DataSet returnDS2 = new DataSet();
//a new sql connection
SqlConnection myConn = new SqlConnection();
myConn.ConnectionString = "Server=myserver.mydomain.com;"
+ "Database=mydatabase;"
+ "User ID=myuserid;"
+ "Password=mypassword;"
+ "Trusted_Connection=True;";
//the sqlQuery
string sqlQuery = "select * from AVLUpdateMessages WHERE ID = 21";
//another ado.net object for the command
SqlCommand cmd = new SqlCommand();
cmd.Connection = myConn;
cmd.CommandText = sqlQuery;
//open the connection, execute the SQL statement and then close the connection.
myConn.Open();
//instantiate and fill the sqldataadapter
dbAdapter = new SqlDataAdapter(cmd);
dbAdapter.Fill(returnDS2, #"AVLUpdateMessages");
//loop through all of the rows; I have verified that the rows are correct and returns the correct data from the db
for (int i = 0; i <= returnDS2.Tables[0].Rows.Count - 1; i++)
{
DataRow row = returnDS2.Tables[0].Rows[i];
row.BeginEdit();
row["UpdatedText"] = #"This is a test...";
row.EndEdit();
}
//let's accept the changes
dbAdapter.Update(returnDS2, "AVLUpdateMessages");
returnDS2.AcceptChanges();
myConn.Close();
}

I think you need an update query in your data adapter. I know, this sucks... Alternatively you can use CommandBuilder class to automatically generate queries for CRUD operations.
example at: http://www.programmersheaven.com/2/FAQ-ADONET-CommandBuilder-Prepare-Dataset

You might be able to use SqlCommandBuilder to help out. After the Fill call, add the following statement. That will associate a command builder with the data adapter and (if there is a primary key available) it should generate the update statement for you. Note that there is some expense behind the command builder. It may not be much relative to everything else, but it does involve looking at schema information (to get primary key information, field names, field types, etc.) for the table and generating INSERT, DELETE, and UPDATE statements involving all fields in the table.
SqlCommandBuilder cb = new SqlCommandBuilder(dbAdapter);

Wait, why not something like
update AVLUpdateMessages set UpdatedText = 'This is a test...' where id = 21
If you're picking through all the rows of a table to update one at a time, you're probably doing it wrong. SQL is your friend.