Develop Reference

simple update query doesn't work, but when i put it into database itself it does work

When i run my code in the debugger and I hover my mouse over the parameters they do have the right values in them. It just doesn't update my database but when I copy the query and put it into the database it works without a problem.
The parameter values are:
id = 7
omschrijving = douche muntjes
prijs = 0,5
catagorie = faciliteiten
I checked the connection tring by using an insert query and that does add records to my database. And There is an id with the value of 7 in the database.
When I run a insert query or a delete query through my C# code it does work it's just the update statement that doesn't work. If anyone sees the issue please help me.
public static void wijzigprijs(int id, string omschrijving, decimal prijs, string catagorie)
{
try
{
try
{
OleDbConnection verbinding = new OleDbConnection(
#"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=..\..\..\La_Rustique.accdb;
Persist Security Info=False;");
verbinding.Open();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
OleDbCommand query = new OleDbCommand();
query.CommandText = #"UPDATE prijslijst
SET omschrijving = #omschrijving,
prijs = #prijs,
catagorie = #catagorie
WHERE id = #id";
query.Parameters.Add(new OleDbParameter("#id", OleDbType.Integer));
query.Parameters["#id"].Value = id;
query.Parameters.Add(new OleDbParameter("#omschrijving", OleDbType.VarChar));
query.Parameters["#omschrijving"].Value = omschrijving;
query.Parameters.Add(new OleDbParameter("#prijs", OleDbType.Decimal));
query.Parameters["#prijs"].Value = prijs;
query.Parameters.Add(new OleDbParameter("#catagorie", OleDbType.VarChar));
query.Parameters["#catagorie"].Value = catagorie;
query.Connection = verbinding;
query.ExecuteNonQuery();
MessageBox.Show("succesvol gewijzigd");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
verbinding.Close();
}
}

EDIT UPDATE
Look at this topic. Here he explains how you should use variables with OleDbCommand
Variables with OleDbCommand
This is how you typically will do it when using SQLCommand parameters:
I know this doesnt answer your questions quite, but when i use SQLCommand i use this code whenever i want to update or insert with variables:
string query = #"UPDATE prijslijst
SET omschrijving = #omschrijving,
prijs = #prijs,
catagorie = #catagorie
WHERE id = #id";
SqlCommand cmd = new SqlCommand(query, connDatabase);
cmd.Parameters.Add("#id", SqlDbType.integer).Value = 7;
cmd.ExecuteNonQuery();
connDatabase.Close();
So you should be able to do the samething. Hope this will help you.

I have never seen OleDB queries written in the above syntax.
To state it differently: OleDB simply does not use named parameters, it uses the position only.
Try to change your SQL statement like this:
query.CommandText = #"UPDATE prijslijst
SET omschrijving = ?,
prijs = ?,
catagorie = ?
WHERE id = ?";
and then add the parameters in sequence of above in the code
below that.

cek valid data in table with input ";" and where in

i want to check valid data...
i have a table Divisi with sample data like this:
=====================
IdDivisi NamaDivisi
=====================
1 DivisiA
2 DivisiB
3 DivisiC
in my code, i get value :
string data = DivisiA;DivXXX
so, when checked, the alert will appear invalid data.
I want to get a query like this:
select NamaDivisi from Divisi where NamaDivisi IN('DivisiA','DivXXX')
and the result is null or empty or invalid.
because there are values ​​/ data 'DivXXX' is not valid on the table Divisi
But this time, when I debug, I get the query result like this:
select NamaDivisi from Divisi where NamaDivisi IN ('DivisiA;DivXXX')
===================================================
This is the full code.
private string CekValidDivisi(string data)
{
DivisiFacade div = new DivisiFacade();
string getDivisi = div.CekValidData(data);
return getDivisi;
}
public string CekValidData(string data)
{
SqlConnection Conn = DataSetting.GetSqlConnection();
SqlCommand Comm = new SqlCommand();
try
{
Conn.Open();
string sql = #"select NamaDivisi from Divisi where NamaDivisi IN('" + data + "')";
Comm = new SqlCommand(sql, Conn);
data = Convert.ToString(Comm.ExecuteScalar());
}
finally
{
Conn.Close();
Conn.Dispose();
}
return data;
}
please help me to resolve the problem in my code. thank you ...

You have multiple problems in your code, but this is not a place to teach you basics, so I'll try to stick to the topic. If you want to have a parameter like that, you have to create it like that first. I guess the data contains string with value DivisiA;DivXXX (and I presume DivXXX is just a generic name meaning you have multiple divisions there). Probably the easiest way would be to do something like this with it
public string CekValidData(string data)
{
SqlConnection Conn = DataSetting.GetSqlConnection();
SqlCommand Comm = new SqlCommand();
try
{
Conn.Open();
string paramData = ParseData(data);
string sql = #"select NamaDivisi from Divisi where NamaDivisi IN('" + paramData + "')";
Comm = new SqlCommand(sql, Conn);
data = Convert.ToString(Comm.ExecuteScalar());
}
finally
{
Conn.Close();
Conn.Dispose();
}
return data;
}
private string ParseData(string data)
{
return data.Replace(";", "','");
}
Haven't tried it, but hope you get the idea. Either way, please for your own sake, do some research on what is the best way to handle sql connections in c# and also how to prevent SQL injections.

how to convert row value from sql server to string in c#

I have a method like this
private string AccountCreation()
{
string accountId="";
using (SqlConnection connection = new SqlConnection(ConnectionString))
{
connection.Open();
SqlCommand command = new SqlCommand();
command.Connection = connection;
StringBuilder sql = new StringBuilder();
sql.AppendLine("SELECT ACCOUNT_ID,CUSTOMER_ID FROM T_ACCOUNT order by ACCOUNT_ID desc");
sql.AppendLine("SET IDENTITY_INSERT T_ACCOUNT ON");
sql.AppendLine("INSERT INTO T_ACCOUNT (ACCOUNT_ID,CUSTOMER_ID)");
sql.AppendLine("SELECT ACCOUNT_ID + 1, CUSTOMER_ID +1 FROM T_ACCOUNT Where ACCOUNT_ID = (select max(ACCOUNT_ID) from T_ACCOUNT)");
sql.AppendLine("SET IDENTITY_INSERT T_ACCOUNT OFF");
accountId = Convert.ToString(sql.AppendLine("SELECT top 1 ACCOUNT_ID FROM T_ACCOUNT order by ACCOUNT_ID desc"));
string strUpdateQuery = sql.ToString();
ExecuteQuery(strUpdateQuery, command);
}
return accountId;
}
Now accountId is holding the query but not the value returned after execution of the query. I want the value in that string. Can anyone help me?

For getting value from the query. you need ExecuteScalar method.
object oRetVal = command.ExecuteScalar();
string accountId = string.Empty;
if(oRetVal != null)
{
accountId = oRetVal.ToString();
}
However, it is recommend to use store procedure.

I assume you are looking for the "TOP 1 Account_ID" from the query. What you have done there will not work (or give you what you want). You will need to either send in a output parameter to put the accountID in, or run fetch the data using datareader or dataset.

You'll have to bind the output of your ExecuteQuery to an object.
check if this returns any result and populates the accID.
var accID = ExecuteQuery(strUpdateQuery, command)

public string ExecuteQuery(string query,SqlCommand cmd)
{
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
object i=cmd.ExecuteScalar();
return i.ToString();
}
After this just assign this to the accounted
accountId = ExecuteQuery(strUpdateQuery, command);

how to reference columns in sql server connection in C#

I'm trying to translate some perl code into C# and I'm having some trouble with the following.
After establishing a sql server connection and executing the select statement, how do I reference the different elements in the table columns. For example, in Perl it looks like:
my $dbh = DBI -> connect( NAME, USR, PWD )
or die "Failed to connect to database: " . DBI->message;
my $dbname = DB_NAME;
my $dbschema = DB_SCHEMA;
my $sql = qq{select a,b,c,d,e,f,g,h,i,...
from $dbname.$dbschema.package p
join $dbname.$dbschema.package_download pd on p.package_id = pd.package_id
join $dbname.$dbschema.download d on pd.download_id = d.download_id
where p.package_name = '$package'
--and ds.server_address like 'tcp/ip'
order by a,b,c,d,..};
my $sth = $dbh -> prepare( $sql )
or die "Failed to prepare statement: " . $dbh->message;
$sth -> execute()
or die "Failed to execute statement: " . $sth->message;
#now to go through each row in result table
while ( #data = $sth->fetchrow_array() )
{
print "$data[0]";
# If source server FTP is not already open, make new FTP
if ( $data[0] != $src_id )
{
if ( $src_ftp )
{ $src_ftp -> quit; }
$src_ftp = make_ftp( $data[1], $data[2], $data[3], $data[18], $data[19], $data[20] );
$src_id = $data[0];
}
}
so far I've got it down to
string db = NAME;
string myConnectionString = "Data Source=ServerName;" + "Initial Catalog=" + db + "User id=" + ODBC_USR + "Password=" + PWD
SqlConnection myConnection = new SqlConnection(myConnectionString);
string myInsertQuery = "select a,b,c,d,e,f,g,h,i,...
from $dbname.$dbschema.package p
join $dbname.$dbschema.package_download pd on p.package_id = pd.package_id
join $dbname.$dbschema.download d on pd.download_id = d.download_id
where p.package_name = '$package'
--and ds.server_address like 'tcp/ip'
order by a,b,c,d,..";
SqlCommand myCommand = new SqlCommand(myInsertQuery);
myCommand.Connection = myConnection;
myConnection.Open();
myCommand.ExecuteNonQuery();
myCommand.Connection.Close();
but how do I reference the columns like data[0] and data[1] in C#. Sorry I'm new to both languages so my background is severely lacking. Thanks!

You could reference your column directly by its column name or by numeric order (it starts with 0 as the first column) either through a DataTable, DataSet, DataReader or a specific DataRow.
For the sake of example i'll use a DataTable here and I will name it as dt and let's say we want to reference the first row then you could reference it with the following Syntax/Format:
dt[RowNumber]["ColumnName or Column Number"].ToString();
For example:
dt[0]["a"].ToString();
Or by number the first column with be 0 like:
dt[0][0].ToString();
And use Parameters by the way because without which it would be susceptible to SQL Injection. Here's a more complete code below:
string db = NAME;
string myConnectionString = "Data Source=ServerName;" + "Initial Catalog=" + db + "User id=" + ODBC_USR + "Password=" + PWD
using (SqlConnection connection = new SqlConnection(myConnectionString))
{
string mySelectQuery = #"SELECT a,b,c,d,e,f,g,h,i,...
FROM package p
JOIN package_download pd on p.package_id = pd.package_id
join download d on pd.download_id = d.download_id
WHERE p.package_name = #PackageName
AND ds.server_address LIKE 'tcp/ip%'
ORDER by a,b,c,d";
try
{
connection.Open();
using (SqlDataAdapter da = new SqlDataAdapter(mySelectQuery, connection))
{
using (SqlCommand cmd = new SqlCommand())
{
da.SelectCommand.Parameters.AddWithValue("#PackageName", txtPackage.Text);
DataTable dt = new DataTable();
da.Fill(dt);
if (dt.Rows.Count>0) // Make sure there is something in your DataTable
{
String aVal = dt[0]["a"].ToString();
String bVal = dt[0]["b"].ToString();
// You'll be the one to fill up
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
I change your LIKE 'tcp/ip' to LIKE 'tcp/ip%' by the way which is the more appropriate one of using LIKE.

you can use ado.net entity data table to reference the tables in your sql server. I don't know if you're asking exactly this but it may help. because direct referencing to sql server is not possible as far as i know.

checking if record exists in Sqlite + C#

I'm trying to check if a record in a table already exists.
How could I do that?
I already wrote the following code:
string dbName = "Data Source=searchindex.db";
SQLiteConnection con = new SQLiteConnection(dbName);
con.Open();
SQLiteCommand cmd = new SQLiteCommand(con);
// If this sql request return false
cmd.CommandText = "SELECT rowid FROM wordlist WHERE word='word'";
cmd.ExecuteNonQuery();
// then add record in table
cmd.CommandText = "INSERT INTO wordlist(word) VALUES ('word')";

To check if that record exists you could simplify your code
cmd.CommandText = "SELECT count(*) FROM wordlist WHERE word='word'";
int count = Convert.ToInt32(cmd.ExecuteScalar());
if(count == 0)
{
cmd.CommandText = "INSERT INTO wordlist(word) VALUES ('word')";
cmd.ExecuteNonQuery();
}
ExecuteScalar will return the first column on the first row returned by your query.
(The link is for SqlServer, but it is identical for SQLite, because the SQLiteCommand should implement the IDbCommand interface)
Another approach to use is the following
cmd.CommandText = "INSERT INTO wordlist (word)
SELECT ('word')
WHERE NOT EXISTS
(SELECT 1 FROM wordlist WHERE word = 'word');";
cmd.ExecuteNonQuery();
This is even better because you use a single query and not two (albeit the difference in a local db should be minimal)

insert into wordlist(word)
select 'foo'
where not exists ( select 1 from wordlist where word = 'foo')

If you are using sqlite-net-pcl you could write the following.
I have a base class for several tables and in it, I have a RowExists method.
The relevant source code looks as follows:
public abstract class BaseSQLiteAccess
{
protected SQLiteConnection _databaseConnection;
protected String TableName { get; set; }
//...
protected bool RowExists(int id)
{
bool exists = false;
try
{
exists = _databaseConnection.ExecuteScalar<bool>("SELECT EXISTS(SELECT 1 FROM " + TableName + " WHERE ID=?)", id);
}
catch (Exception ex)
{
//Log database error
exists = false;
}
return exists;
}
}