Develop Reference

Checking if int exists in array C#

I don’t know if this is the correct way to be doing this but I'm trying to get all Job Numbers from a database table and checking that what the user inputs is in the database. I’m doing this by sending all data to an array and checking if it exists in there. However I’m sure there will be an easier way. This is the code I have so far:
public class IDNo
{
public int Col1 { get; set; }
}
private void button3_Click(object sender, EventArgs e)
{
String check = "SELECT * FROM Job";
using (SqlConnection con = new SqlConnection(str))
{
using (SqlCommand cmd = new SqlCommand(check, con))
{
con.Open();
var listOfId = new List<IDNo>();
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var id = new IDNo();
id.Col1 = Convert.ToInt32(reader["JobNo"]);
listOfId.Add(id);
}
}
string JN = textBox10.Text;
int JoNo = Int32.Parse(JN);
if (JoNo == IDNo)
{
MessageBox.Show("No job number found, please try again!");
}
else
{
DO SOMETHING HERE WHEN CORRECT
}
}
}
}
I would just like some help on how to check if the number the user inputs exists in the array.

It is the database engine that should answer your question, not simply give you back all your job records and force your code through a, possible, very lengthy search of the matching data in your records...
int JoNo;
if(!Int32.TryParse(textBox10.Text, out JoNo))
{
MessageBox.Show("Not a valid number");
return;
}
String check = #"IF EXISTS( SELECT 1 FROM Job WHERE JobNo=#num)
SELECT 1 ELSE SELECT 0";
using (SqlConnection con = new SqlConnection(str))
using (SqlCommand cmd = new SqlCommand(check, con))
{
con.Open();
cmd.Parameters.Add("#num", SqlDbType.Int).Value = JoNo;
int result = (int)cmd.ExecuteScalar();
if(result == 0)
MessageBox.Show("No job number found, please try again!");
else
.....
}
First, you test if the user input is a valid number without throwning exceptions (Int32.TryParse) but just informing your user of the error, then you build an IF EXISTS query because you are just interested to know if the job number exists or not and you don't need to retrieve that value. Finally, the execution is done using ExecuteScalar because you are interested only in getting the single value 1 (for an existing JobNo or 0 for a not exisisting JobNo.

You can use the jobNo which is sent by the user as an input parameter for your search query in database. So you can simply do it using the query:
SqlCommand check = new SqlCommand("SELECT * FROM Job where JobNo = #JobNo" , conn);
check.Parameters.AddWithValue("#JobNo", id.Text);
int exists = (int)check.ExecuteScalar();
if(exists > 0)
{
//job no exist
}
else
{
//job no doesn't exist.
}

Mysql read and change variable at the same time

I want to shift some variables by one. I searched for the command for it but I couldn't find. If anybody knows it please help me.
Here is the code:
private int shiftNumbers(int number)
{
int newNumber = 0;
string stm = "UPDATE devices SET number= #newNumber WHERE number>#number";
try
{
con.Open();
cmd = new MySqlCommand(stm, con);
cmd.Parameters.AddWithValue("#number", number);
}
catch (Exception e)
{
ErrorMessage = e.Message;
con.Close();
return null;
}
try
{
rdr = cmd.ExecuteReader();
while(rdr.Read()) {
newNumber = rdr.GetInt32(1);
cmd.Parameters.AddWithValue("#newNumber ", (newNumber-1));
}
}
catch (Exception e)
{
ErrorMessage = e.Message;
con.Close();
return null;
}
con.Close();
return 1;
}
I know this code useless but I show it for you to get the logic that I want to do.

I think your approach is wrong.
First, you read from the database, using a select statement;
Then you go over that result, your rdr.Read();
Then you create a new command, updating the original record;
Move forward in your reader (rdr) and repeat from 2 until you are done.
What you are doing now is impossible. You can't get a result set from an update, just a count affected.
Or, if you can, let your update statement do the calculation (it seems it is only subtracting one from the original number, so why not do that in SQL?):
string stm = "UPDATE devices SET number = number - 1 WHERE number>#number";

Yes, your code is really useless. In your update statement you are passing a parameter #newNumber bu not providing it. Closing the connection in catch block.
string stm = "UPDATE devices SET number= #newNumber WHERE number>#number";
First decide from where you are going to get the #newNumber value and then add that as parameter and use ExecuteNonQuery() method.
If you want pass the other parameter as well in your method and use it like
private int shiftNumbers(int number, int newNumber)
{
//int newNumber = 0;
string stm = "UPDATE devices SET number= #newNumber WHERE number>#number";
using(SqlConnection con = new SqlConnection(connectionString))
{
cmd = new MySqlCommand(stm, con);
SqlParameter paramNumber = new SqlParameter("#number", SqlDbType.Int);
paramNumber.Value = number;
SqlParameter paramNewNumber = new SqlParameter("#newNumber", SqlDbType.Int);
paramNewNumber.Value = newNumber;
cmd.Parameters.Add(paramNumber);
cmd.Parameters.Add(paramNewNumber);
con.Open();
cmd.ExecuteNonQuery();
}
//Rest of your code logic if any
}

Auto generate and AutoIncrement ID in C# when trying to add new record to database

I'm using this code to select the maxID from a database table and each time I want to add a new record, the autogenerated ID is not the last one +1.
public formularAddCompanie()
{
InitializeComponent();
try
{
string cs = "Data Source=CODRINMA\\CODRINMA;Initial Catalog=TrafficManager;Integrated Security=True";
string select = "SELECT max(IDCompanie) FROM Companii";
using (SqlConnection con = new SqlConnection(cs))
{
con.Open();
SqlCommand cmd2 = new SqlCommand(select, con);
SqlDataReader sda = cmd2.ExecuteReader();
DataTable idmax = new DataTable("idmax");
idmax.Load(sda);
if (idmax.Rows[0][0].ToString().Trim() == "") { txtID.Text = "1"; }
else { txtID.Text = (int.Parse(idmax.Rows[0][0] .ToString() + 1).ToString()); }
}
}
catch (Exception er) { MessageBox.Show(er.Message); }
}
The table from where the selection is made, looks like this:
IDCompany Name Address City RegNo
1 A Street NY 123
Each time I want to add a new record, the autogenerated ID is like this: 11, 111, 1111. It takes the last ID and add another 1 next to it. What am I missing?

Interestingly, note that
string a = "The meaning of life is " + 42;
converts 42 to a string, creating the result
a == "The meaning of life is 42"
Look at this code:
(int.Parse(idmax.Rows[0][0] .ToString() + 1).ToString()); }
You are converting idmax.Rows[0][0] to a string and adding +1 to the end of the string rather than to an integer value. Try
(int.Parse(idmax.Rows[0][0].ToString()) + 1).ToString(); }
Note that idmax.Rows[0][0] should already have an integer in it (as pointed out in the comments). If that's the case, you can simplify to
(idmax.Rows[0][0] + 1).ToString(); }

idmax.Rows[0][0].ToString() + 1 produces string, not int.
You can try
txtID.Text = (Convert.ToInt32(idmax.Rows[0][0]) + 1).ToString();

I just add this because it seems that none cares about the weakness of the code posted by the poster.
First the MAX function is not reliable if you want to find the next autoincrement value that will be assigned to an ID column. Concurrency could wreak havoc with any schema that use MAX. Just suppose that another user has already retrieved the MAX for its own INSERT operation, then depending on the relative speed of the two computers you or the other user will insert a duplicate value for the IDCompany field.
The only correct way to do this common task is to use the IDENTITY property for the column IDCompany and when you need to insert a new record you should write something like this
try
{
string insert = "INSERT INTO Companii (Name,Address,City,RegNo)
VALUES(#name,#address,#city,#regno);
SELECT SCOPE_IDENTITY()";
using (SqlConnection con = new SqlConnection(cs))
using (SqlCommand cmd = new SqlCommand(insert, con))
{
con.Open();
cmd.Parameters.Add("#name", SqlDbType.NVarChar).Value = txtBoxCity.Text;
.... and on for the other parameters ....
int companyID = Convert.ToInt32(cmd.ExecuteScalar());
... work with the just added company if required
}
}
catch (Exception er)
{ MessageBox.Show(er.Message); }
SCOPE_IDENTITY will return the last identity value inserted into an identity column in the same scope and in this context scope means the connection used by your command.
In any case, if the MAX approach is still required then the code could be simplified a lot using a modified query and SqlCommand.ExecuteScalar instead of building an SqlDataReader, filling a datatable, trying to parse the result with ifs
string getMax = #"select COALESCE(MAX(IDCompany), 0) + 1 AS maxPlusOne
from Companii"
using(SqlConnection cnn = new SqlConnection(.....))
using(SqlCommand cmd = new SqlCommand(getMax, cnn))
{
cnn.Open();
int nextCompanyID = Convert.ToInt32(cmd.ExecuteScalar());
}
The COALESCE function checks the result of the MAX function and if it is NULL returns the second parameter (here 0), then just increment by 1 to get the next MAX directly from the database. ExecuteScalar will do the call returning just the maxPlusOne alias field

try this snippet:
Convert Your String into Int. String with + operator will con-cat and with int it will add numbers.
if (idmax.Rows[0][0].ToString().Trim() == "") { txtID.Text = "1"; }
else {
txtID.Text = Convert.ToString(Convert.ToInt32(idmax.Rows[0][0] .ToString())+1); }

Try This one, my id format is USR001.The code will generate auto id based on the last id inside the database. If the last id in the database is USR001, the the code will generate USR002 and put the id to the textbox
con.Open();
string sqlQuery = "SELECT TOP 1 kode_user from USERADM order by kode_user desc";
SqlCommand cmd = new SqlCommand(sqlQuery, con);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
string input = dr["kode_user"].ToString();
string angka = input.Substring(input.Length - Math.Min(3, input.Length));
int number = Convert.ToInt32(angka);
number += 1;
string str = number.ToString("D3");
txtKodeUser.Text = "USR" + str;
}
con.Close();

MySqlCommand: no rows returned

I have a database created in a server and I added a row by MySql query browser for testing. This row is visible either with PhpMyAdmin or MySql query browser.
But when I want to reach this table within my program it says me there is no rows (reader.HasRows = false)
cs is the connection string in PublicVariables class
Here is the code
public static int checkuser(string myuser, string mypass)
{
try
{
using (MySqlConnection conn = new MySqlConnection(PublicVariables.cs))
{
string MypassMd5 = MakeMD5(mypass);
conn.Open();
if (conn == null)
Environment.Exit(0);
using (MySqlCommand cmd =
new MySqlCommand("SELECT username, password " + "FROM Users WHERE username = 'myuser'" ,conn))
{
using (MySqlDataReader reader = cmd.ExecuteReader())
{
//DateTime mytime = DateTime.Now ;
if (reader.HasRows)
{
if (Convert.ToString(reader["password"]) != MypassMd5)
{
reader.Close();
conn.Close();
return -1;
}
else
{
PublicVariables.UserId = Convert.ToString(reader["username"]);
PublicVariables.UserDegre = Convert.ToInt16(reader["userdegre"]);
conn.Close();
reader.Close();
return 1;
}
}
else
{
reader.Close();
conn.Close();
return 2;
}
}
}
}
}
catch (MySqlException ex)
{
MessageBox.Show(ex.ToString());
}
return 0;
}
What's wrong in my code?

Well the primary error is in your command string , myuser is a variable and you cannot pass its value putting the variable name inside quotes.
new MySqlCommand("SELECT username, password FROM Users WHERE username = 'myuser'" ,conn)
instead this line should be converted to use a parameterized query
string commandText = "SELECT username, password, userdegre FROM Users WHERE username = #uname";
using (MySqlCommand cmd = new MySqlCommand(commandText ,conn)
{
cmd.Parameters.AddWithValue("#uname", myuser);
....
Looking at your code you have another error after this. You try to read the field userdegre, but this field is not retrieved by your query, so you need to add it to the list of retrieved fields.
But the only field you really need to know is userdegre because you already know the username and the password, so you could remove the datareader and use ExecuteScalar and pass the username and the password as parameters for the WHERE clause. If you get anything in return then you are sure that your user is authenticated by the database.
string commandText = "SELECT userdegre FROM Users WHERE username = #uname AND Password =#pwd";
using(MySqlCommand cmd = new MySqlCommand( commandText ,conn))
{
cmd.Parameters.AddWithValue("#uname", myuser);
cmd.Parameters.AddWithValue("#pwd", MypassMd5);
var result = cmd.ExecuteScalar();
if(result != null)
{
PublicVariables.UserId = myuser;
PublicVariables.UserDegre = result.ToString();
}
}

Don't check reader.HasRows. You need to call reader.Read(), and check the result of that.
Also, some side issues:
MD5 is incredibly weak for a password hash. Really. Just don't use it for that. Look into bcrypt as a much better alternative. Better still if you're not writing authentication code yourself at all. Look for a library for help to get this stuff right... it's just so easy to write authentication code that seems to work, passes all your tests, but has a subtle flaw that gets you hacked a few months down the road.
No need to call conn.Close(). That's what your using blocks are for. They will handle this for you.
I'd remove the try/catch as well. Since you're already returning error conditions to the calling code, I'd leave that as the place where errors are processed, such that your try/catch should go at that level.
You're looking for userdegre in the results that was not in the select list.
Parameterized queries are your friend.
Put it all together you and you end up with this:
public static int checkuser(string myuser, string mypass)
{
string passHash = BCrypt(mypass); //Need to get bcyrpt library and make the function
using (MySqlConnection conn = new MySqlConnection(PublicVariables.cs))
using (MySqlCommand cmd =
new MySqlCommand("SELECT username, password, userdegre FROM Users WHERE username = #user" ,conn))
{
cmd.Parameters.Add("#user", SqlDbType.NVarChar, 20).Value = myuser;
conn.Open();
using (MySqlDataReader reader = cmd.ExecuteReader())
{
if (!reader.Read()) return 2;
if (Convert.ToString(reader["password"]) != MypassMd5) return -1;
PublicVariables.UserId = Convert.ToString(reader["username"]);
PublicVariables.UserDegre = Convert.ToInt16(reader["userdegre"]);
return 1;
}
}
}

I would try something like this new MySqlCommand("SELECT username, password, userdegre " + "FROM Users WHERE username = 'myuser'" ,conn))
adding userdegre the column name in your select statement.

Finally for c# 2008 net 3.5 WORKING COPY of this after the help of #Joel and # Steve is as this:
public static int usertrue(string myuser, string mypass)
{
try
{
using (MySqlConnection conn = new MySqlConnection(PublicVariables.cs))
{
string MypassMd5 = MakeMD5(mypass);
using (MySqlCommand cmd =
new MySqlCommand("SELECT username, password ,userdegre FROM Users WHERE username = #user",conn))
{
cmd.Parameters.Add("#user", MySqlDbType.VarChar, 15).Value = myuser;
conn.Open();
using (MySqlDataReader reader = cmd.ExecuteReader())
{
if (!reader.Read()) return 2;
if (Convert.ToString(reader["password"]) != MypassMd5) return -1; {
PublicVariables.UserId = Convert.ToString(reader["username"]);
PublicVariables.UserDegre = Convert.ToInt16(reader["userdegre"]);
return 1;
}
}
}
}
}

Why does disposing a SqlCeConnection both solve one exception and raise a different one?

When calling the same query method twice in a session of the app, I get "DBCommandExcept"
As an experiment, I decided to dispose of the connection object at the end of the method, to see if that was the problem.
I no longer get the DBCommandExcept err msg, but instead get, "the connectionstring property has not been initialized."
IOW, it's sort of a Catch-22 situation at the moment. The pertinent code is:
string query = "SELECT Bla FROM Blah";
SqlCeCommand cmd = new SqlCeCommand(query);
cmd.CommandType = CommandType.Text;
SqlCeConnection conn = dbconn.GetConnection();
cmd.CommandType = CommandType.Text;//probably unnecessary
cmd.Connection = conn;
SqlCeDataReader myReader = cmd.ExecuteReader(CommandBehavior.SingleRow);
try
{
if (myReader.Read())
{
itemID = myReader.GetString(ITEMID_INDEX);
packSize = myReader.GetString(PACKSIZE_INDEX);
recordFound = true;
}
}
catch (Exception ex)
{
RRDR.LogMsgs.Append(string.Format("Exception in PopulateControlsIfVendorItemsFound(): {0}", ex.Message));
}
finally
{
myReader.Close();
//if (null != conn)
//{
// conn.Dispose();
//}
}
// Re: the commented-out block above: When it is active, the DBCommandExcept problem is not seen; however, I then get, "the connectionstring property has not been initialized"
I think the only non-SQL-CE-standard bit above is the dbConn.GetConnection(). Here's some of that code:
SqlCeConnection objCon = null;
. . .
public SqlCeConnection GetConnection()
{
return objCon;
}
private DBConnection() // class constructor
{
try
{
. . .
objCon = new SqlCeConnection(conStr);
objCon.Open();
. . .
Again, the error (either one, whichever one I "choose" to have) is seen only the second time through this method during one run of the app. The first time works fine.
UPDATE
I added the code below, and the comments tell the tale of woe:
// With conn check only, still get two consecutive DBCommandExcepts
// With cmd check only, still get two consecutive DBCommandExcepts
// With both, still get two consecutive DBCommandExcepts; IOW, all have the same effect
if (null != conn)
{
conn.Close();
}
if (null != cmd)
{
cmd.Dispose();
}
UPDATE 2
Based on unicron's suggestion, I tried using "using."
In two of the three cases (SqlCeCommand and SqlCeDataReader), converting to "using" made no diff; in the other one (SqlCeConnection), it raised the err msgs, "The ConnectionString property has not been initialized."
Still, though, the code is cleaner with the two usings, so thanks for that nudge in the best practices direction.
Here's what it looks like now:
private bool PopulateControlsIfPlatypusItemsFound()
{
const int ITEMID_INDEX = 0;
const int PACKSIZE_INDEX = 1;
bool recordFound = false;
try
{
string PlatypusId = txtPlatypus.Text.ToString().Trim();
string PlatypusItemId = txtUPC.Text.ToString().Trim();
string itemID = string.Empty;
string packSize = string.Empty;
string query = string.Format("SELECT ItemID, PackSize FROM PlatypusItems WHERE PlatypusID = {0} AND PlatypusItemID = {1}", PlatypusId, PlatypusItemId);
using (SqlCeCommand cmd = new SqlCeCommand(query))
{
cmd.CommandType = CommandType.Text;
SqlCeConnection conn = dbconn.GetConnection();
if ((null != conn) && (!conn.State.Equals(ConnectionState.Open)))
{
conn.Open();
TTBT.LogMsgs.Append("Connection opened");
}
cmd.CommandType = CommandType.Text;//probably unnecessary
cmd.Connection = conn;
using (SqlCeDataReader myReader = cmd.ExecuteReader(CommandBehavior.SingleRow))
{
if (myReader.Read())
{
itemID = myReader.GetString(ITEMID_INDEX);
packSize = myReader.GetString(PACKSIZE_INDEX);
recordFound = true;
}
}
txtID.Text = itemID;
txtSize.Text = packSize;
return recordFound;
}
}
catch (Exception ex)
{
TTBT.LogMsgs.Append(string.Format("Exception in PopulateControlsIfPlatypusItemsFound: {0} - {1}\r\n", ex.Message, ex.InnerException));
return recordFound;
}
}
UPDATE 3
I've come even closer to normalcy by replacing the custom connection code with the generic sort, adding another "using" to the mix:
private bool PopulateControlsIfVendorItemsFound()
{
const int ITEMID_INDEX = 0;
const int PACKSIZE_INDEX = 1;
bool recordFound = false;
DUCKBILL.LogMsgs.Append("Made it into frmEntry.PopulateControlsIfVendorItemsFound()\r\n");
try
{
string vendorId = txtVendor.Text.ToString().Trim();
string vendorItemId = txtUPC.Text.ToString().Trim();
string itemID = string.Empty;
string packSize = string.Empty;
if ( dbconn.isValidTable( "VendorItems" ) == -1 )
{
DUCKBILL.LogMsgs.Append("VendorItems not a valid table");//do not see this msg; good! VendorItems is seen as valid...
return false;
}
string query = string.Format("SELECT ItemID, PackSize FROM VendorItems WHERE VendorID = {0} AND VendorItemID = {1}", vendorId, vendorItemId);
using (SqlCeCommand cmd = new SqlCeCommand(query))
{
cmd.CommandType = CommandType.Text;
using (SqlCeConnection conn = new SqlCeConnection())
{
string filename = "\\badPlace2B\\CCRDB.SDF";
conn.ConnectionString = string.Format("Data Source = {0}", filename);
cmd.CommandType = CommandType.Text;//probably unnecessary/moot
cmd.Connection = conn;
conn.Open();
using (SqlCeDataReader myReader = cmd.ExecuteReader(CommandBehavior.SingleRow))
{
if (myReader.Read())
{
itemID = myReader.GetString(ITEMID_INDEX);
packSize = myReader.GetString(PACKSIZE_INDEX);
recordFound = true;
}
}
}
txtID.Text = itemID;
txtSize.Text = packSize;
return recordFound;
}
}
catch (Exception ex)
{
DUCKBILL.LogMsgs.Append(string.Format("Exception in PopulateControlsIfVendorItemsFound: {0} - {1}\r\n", ex.Message, ex.InnerException));
return recordFound;
}
}
...yet I still get "DBCommandExcept"...
As to "stop futzing around with opening the connection," isn't it necessary to do so? How could/should the code above be different?
UPDATE 4
What is even more bizarre is that now my debug log file has stopped being written. I have been writing it out both in the global exception handler AND in the main form's Closed event(), and it always has (until now) at least a few entries, but within the last couple of updates to the code, it is no longer being written...????
Both places global exception handler and main form's Closed event(), the code is like so:
public static bool inDebugMode = true;
. . .
if (CCR.inDebugMode)
{
DateTime dt = DateTime.Now;
string timeAsStr = string.Format("{0}_{1}_{2}_{3}.txt", dt.Hour, dt.Minute, dt.Second, dt.Millisecond);
using (StreamWriter file = new StreamWriter(timeAsStr))
{
// If the app closes normally, this is how the file is written; if it doesn't,
// (it crashed) it's written in PDAClient.ExceptionHandler()
file.WriteLine(SSCS.LogMsgs.ToString());
}
}

Since you are making several calls to a database file (that isn't going to change), I'd start out by defining your connection string and your SQL statements at the top of your class as global values:
private const int ITEMID_INDEX = 0;
private const int PACKSIZE_INDEX = 1;
private const string SQL_CONN_STR = "Data Source=\\badPlace2B\\CCRDB.SDF";
private const string SQL_GET_VENDOR_ITEMS = "SELECT ItemID, PackSize " +
"FROM VendorItems " +
"WHERE VendorID=#VendorID AND VendorItemID=#VendorItemID";
These never change, so there is no reason to define them again each time you call your routine.
Personally, I do not like inserting values into SQL statements, like you have shown. Rather, try to use Parameters.
To use Parameters, you'll need to look into your database to see what type of columns VendorID and VendorItemID are. My guess is that they are both int values, but these could be GUID like values, requiring VarChar type strings. If these are strings, you should write down what sizes the columns are defined as.
For example: Below, my Serial_Number column is the SqlDbType.NVarChar and the size is 50. An SqlCeParameter for this column would be:
cmd.Parameters.Add("#Serial_Number", SqlDbType.NVarChar, 50).Value = txtSerial_Number.Text.Trim();
Since I did not know what type of data you use, I created an enumerated type to show how each method would be used. If you do not have access to the table's design, the last resort is "AddWithValue" (I personally hate that one, because it makes me look like I don't know what my database has inside).
enum ParamStyle { AddWithValue, AddIntegers, AddVarChar }
To use this enumerated type, I modified the signature of your method to pass in that value:
private bool PopulateControlsIfVendorItemsFound(ParamStyle style) {
Obviously, you will not need this, because you should know what technique you are going to be coding with.
I wasn't able to figure out what your dbconn object was. Initially, I thought this was your SqlCeConnection, but that does not have an isValidTable method, so I just commented it out:
//if (dbconn.isValidTable("VendorItems") == -1) {
// DUCKBILL.LogMsgs.Append("VendorItems not a valid table");//do not see this msg; good! VendorItems is seen as valid...
// return false;
//}
Speaking of SqlCeConnection...
I combined your SqlCeCommand instance with your SqlCeConnection instance. Less code typically means fewer errors:
using (var cmd = new SqlCeCommand(SQL_GET_VENDOR_ITEMS, new SqlCeConnection(SQL_CONN_STR))) {
The CommandType, by default, is CommandType.Text, so this line is unnecessary:
// cmd.CommandType = CommandType.Text; (this is the default)
I moved most of your variable reading outside of the try/catch routine, as none of that should ever cause an exception to be generated.
Also, I used the more targeted SqlCeException instead of the general Exception. The only thing that could fail in the block is something SqlCe related, and the SqlCeException will give you better/more specific error messages than the general Exception object will.
} catch (SqlCeException err) {
So, what does it look like all put together?
Code:
enum ParamStyle { AddWithValue, AddIntegers, AddVarChar }
private const int ITEMID_INDEX = 0;
private const int PACKSIZE_INDEX = 1;
private const string SQL_CONN_STR = "Data Source=\\badPlace2B\\CCRDB.SDF";
private const string SQL_GET_VENDOR_ITEMS = "SELECT ItemID, PackSize FROM VendorItems WHERE VendorID=#VendorID AND VendorItemID=#VendorItemID";
private bool PopulateControlsIfVendorItemsFound(ParamStyle style) {
bool recordFound = false;
//DUCKBILL.LogMsgs.Append("Made it into frmEntry.PopulateControlsIfVendorItemsFound()\r\n");
string itemID = null;
string packSize = null;
//string vendorId = txtVendor.Text.Trim();
//string vendorItemId = txtUPC.Text.Trim();
//string query = string.Format("SELECT ItemID, PackSize FROM VendorItems WHERE VendorID = {0} AND VendorItemID = {1}", vendorId, vendorItemId);
//if (dbconn.isValidTable("VendorItems") == -1) {
// DUCKBILL.LogMsgs.Append("VendorItems not a valid table");//do not see this msg; good! VendorItems is seen as valid...
// return false;
//}
using (var cmd = new SqlCeCommand(SQL_GET_VENDOR_ITEMS, new SqlCeConnection(SQL_CONN_STR))) {
// cmd.CommandType = CommandType.Text; (this is the default)
if (style == ParamStyle.AddIntegers) { // Adding Integers:
cmd.Parameters.Add("#VendorID", SqlDbType.Int).Value = Convert.ToInt32(txtVendor.Text.Trim());
cmd.Parameters.Add("#VendorItemID", SqlDbType.Int).Value = Convert.ToInt32(txtUPC.Text.Trim());
} else if (style == ParamStyle.AddVarChar) { // Adding String Values
// NOTE: Here, you should look in your database table and
// use the size you defined for your VendorID and VendorItemID columns.
cmd.Parameters.Add("#VendorID", SqlDbType.VarChar, 25).Value = txtVendor.Text.Trim();
cmd.Parameters.Add("#VendorItemID", SqlDbType.VarChar, 50).Value = txtUPC.Text.Trim();
} else if (style == ParamStyle.AddWithValue) { // Adding as Objects (only if you don't know what the data types are)
cmd.Parameters.AddWithValue("#VendorID", txtVendor.Text.Trim());
cmd.Parameters.AddWithValue("#VendorItemID", txtUPC.Text.Trim());
}
try {
cmd.Connection.Open();
using (var myReader = cmd.ExecuteReader(CommandBehavior.SingleRow)) {
if (myReader.Read()) {
itemID = myReader.GetString(ITEMID_INDEX);
packSize = myReader.GetString(PACKSIZE_INDEX);
recordFound = true;
}
}
} catch (SqlCeException err) {
//DUCKBILL.LogMsgs.Append(string.Format("Exception in PopulateControlsIfVendorItemsFound: {0}\r\n", err.Message));
// (I never return from a 'catch' statement) return recordFound;
} finally {
if (cmd.Connection.State == ConnectionState.Open) {
cmd.Connection.Close();
}
}
}
if (recordFound) { // set these last, and set them OUTSIDE of the try/catch block
txtID.Text = itemID;
txtSize.Text = packSize;
}
return recordFound;
}
Happy Coding!