I have following class that connects to database but when I trye to call the method that saves data I get error "Database is locked". Could some one please help me to find the problem?
class Data
{
private SQLiteConnection con;
private void ConnectoDB()
{
String PathDB = Directory.GetCurrentDirectory();
PathDB += "\\SQLiteDB_MEDFit.db";
string cs = #"URI=file:" + PathDB;
string stm = "SELECT SQLITE_VERSION()";
con = new SQLiteConnection(cs);
con.Open();
var cmd = new SQLiteCommand(stm, con);
string version = cmd.ExecuteScalar().ToString();
}
public Boolean SaveToDatabase(string name, string number)
{
bool result = false;
try
{
ConnectoDB();
con.Execute("insert into People(name, number) values ('" + name+ "', '" + number+ "')");
con.Close();
result = true;
MessageBox.Show("Saved!");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
return result;
}
}
The code that calls the "SaveToDatabase()"
string name = textBox1.Text();
string number = textBox2.Text();
Data connect = new Data();
connect.SavetoDB(name, number);
I'm working with two stored procedures in an ASP.NET button function. While I get an error message based on the results that the invoice number is already dispatched from the other stored procedure, it still moves to the other stored procedure and executes it.
If the user gets this error message:
This invoice num was already dispatched!
then it shouldn't move on to this aspect of the function
protected void Button2_Click(object sender, EventArgs e)
{
try
{
for (int i = GridView2.Rows.Count - 1; i >= 0; i--)
{
var row = GridView2.Rows[i];
CheckBox chk = row.FindControl("chkInvoice") as CheckBox;
//CheckBox chk = (CheckBox)GridView2.Rows[i].Cells[0].FindControl("CheckBox3");
if (chk != null && chk.Checked)
{
string strSQLconstring = System.Configuration.ConfigurationManager.ConnectionStrings["TWCL_OPERATIONSConnectionString"].ToString();
using (SqlConnection objConnection = new SqlConnection(strSQLconstring))
{
objConnection.Open();
using (SqlTransaction transaction = objConnection.BeginTransaction())
{
string SID = GridView2.Rows[i].Cells[3].Text.Trim();
SqlDataReader myReader = null;
using (SqlCommand command = new SqlCommand("PP_SelectStatus", objConnection, transaction))
{
command.CommandType = CommandType.StoredProcedure;
command.Parameters.AddWithValue("#invoiceNum", SID);
command.Parameters.AddWithValue("#custPONum", GridView2.Rows[i].Cells[4].Text.Trim());
myReader = command.ExecuteReader();
if (myReader.Read())
{
string invoice1 = (myReader["status"].ToString());
if (invoice1 == "0")
{
ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('This invoice num was already dispatched!')", true);
}
myReader.Close();
}
}
else if (invoice1=="1")
{
using (SqlCommand cmd = new SqlCommand("PP_RemoveInvoice", objConnection, transaction))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#loadSheetNum", txtDispatchNum.Text);
cmd.Parameters.AddWithValue("#invoiceNum", SID);
cmd.Parameters.AddWithValue("#removeUser", lblUsername.Text.Replace("Welcome", ""));
**int a = cmd.ExecuteNonQuery();**
cmd.Dispose();
if (a > 0)
{
dt.Rows.RemoveAt(i);
////Read invoice qty from grid view 2
string invoice = GridView2.Rows[i].Cells[5].Text.ToString();
decimal invoiceTotal = Convert.ToDecimal(txtInvoiceTotal.Text) - Convert.ToDecimal(invoice);
txtInvoiceTotal.Text = invoiceTotal.ToString();
////Read invoice weight from grid view 2
string weight = GridView2.Rows[i].Cells[6].Text.ToString();
decimal invoiceWeight = Convert.ToDecimal(txtQtyWeight.Text) - Convert.ToDecimal(weight);
txtQtyWeight.Text = invoiceWeight.ToString();
lblError.ForeColor = Color.Green;
lblError.Text = "Selected record(s) successfully updated";
}
else
{
lblError.ForeColor = Color.Red;
lblError.Text = " Record has not yet been recorded";
}
}
//objConnection.Close();
transaction.Commit();
}
}
}
//Button2.Visible = false;
//showData();
GridView2.DataSource = dt;
GridView2.DataBind();
txtInvoiceCount.Text = dt.Rows.Count.ToString();
}
}
}
catch (Exception ex)
{
if (ex.Message.StartsWith("Violation of PRIMARY KEY constraint"))
{
lblError.ForeColor = Color.Red;
lblError.Text = " This invoice number was remove from dispatch sheet before!!";
}
else
{
// re-throw the error if you haven't handled it
lblError.Text = ex.Message;
throw;
}
}
}
You have a very, very simple logic error, but it is incredibly hard to see because your code is such a mess. Therefore, my answer is:
REFACTOR REFACTOR REFACTOR
It is important to get into the habit of writing short functions and controlling their inputs and outputs. If you don't do this, even a fairly trivial operation like this one gets very confusing and error-prone.
Here is an example of how to organize things. We remove most of the code from the click handler:
protected void DeleteButton_Click(object sender, EventArgs e)
{
for (int i = GridView2.Rows.Count - 1; i >= 0; i--)
{
var row = GridView2.Rows[i];
if (IsChecked(row))
{
var result = ProcessRow(row, i);
DisplayResult(i, result);
}
}
}
Firstly, notice it has a meaningful name. These become very important as your application grows. Also, look how short it is! Where did all the code go? Well, it went into two separate methods, which are now short enough for us to view on one page-- a common requirement that IT organizations impose on their programmers, to avoid spaghetti code.
protected TransactionResult ProcessRow(GridViewRow row, int index)
{
var SID = GridView2.Rows[index].Cells[3].Text.Trim();
var custPONum = GridView2.Rows[index].Cells[4].Text.Trim();
var loadSheetNum = txtDispatchNum.Text;
var removeUser = lblUsername.Text.Replace("Welcome", "");
return ExecuteInvoiceTransaction(SID, custPONum, loadSheetNum, removeUser);
}
And
public void DisplayResult(int rowIndex, TransactionResult result)
{
switch result
{
case TransactionResult.Success:
dt.Rows.RemoveAt(rowIndex);
DisplayTotals(rowIndex);
DisplaySuccess("Selected record(s) successfully updated");
break;
case TransactionResult.AlreadyDispatched;
ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('This invoice num was already dispatched!')", true);
break;
case TransactionResult.RecordNotRecorded;
DisplayError("Record has not yet been recorded");
break;
case TransactionResult.AlreadyRemoved:
DisplayError("This invoice number was remove from dispatch sheet before!!");
break;
}
}
These methods in turn call a variety of helper methods, each of which does one thing and one thing only. This could be referred to as separation of concerns, which is really important for structured code.
Here's the rest of the methods:
enum TransactionResult
{
Success,
AlreadyDispatched,
RecordNotRecorded,
AlreadyRemoved
}
private bool ExecuteSelectStatus(SqlConnection connection, SqlTransaction transaction, string invoiceNum, string custPONum)
{
using (SqlCommand command = new SqlCommand("PP_SelectStatus", objConnection, transaction))
{
command.CommandType = CommandType.StoredProcedure;
command.Parameters.AddWithValue("#invoiceNum", invoiceNum);
command.Parameters.AddWithValue("#custPONum", custPONum);
using (var myReader = command.ExecuteReader())
{
if (myReader.Read())
{
string invoice1 = (myReader["status"].ToString());
if (invoice1 == "0")
{
return false;
}
}
}
return true;
}
}
private int ExecuteRemoveInvoice(SqlConnection objConnection, SqlTransaction transaction, string loadSheetNum, string invoiceNum, string removeUser)
{
try
{
using (SqlCommand cmd = new SqlCommand("PP_RemoveInvoice", objConnection, transaction))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#loadSheetNum", loadSheetNum);
cmd.Parameters.AddWithValue("#invoiceNum", invoiceNum);
cmd.Parameters.AddWithValue("#removeUser", removeUser);
return cmd.ExecuteNonQuery();
}
}
catch (SqlException ex)
{
if (ex.Number == 2627) //Primary key violation
{
return -1;
}
}
}
protected TransactionResult ExecuteInvoiceTransaction(string invoiceNum, string custPONum, string loadSheetNum, string removeUser)
{
var strSQLconstring = System.Configuration.ConfigurationManager.ConnectionStrings["TWCL_OPERATIONSConnectionString"].ToString();
using (SqlConnection objConnection = new SqlConnection(strSQLconstring))
{
objConnection.Open();
using (SqlTransaction transaction = objConnection.BeginTransaction())
{
var ok = ExecuteSelectStatus(objConnection, transaction, invoiceNum, custPONum);
if (!ok) return TransactionResult.AlreadyDispatched;
var a = ExecuteRemoveInvoice(objConnection, transaction, loadSheetNum, invoiceNum, removeUser);
switch a
{
case -1:
return TransactionResult.AlreadyRemoved;
case 0:
return TransactionResult.RecordNotRecorded;
default:
transaction.Commit();
return TransactionResult.Success;
}
}
}
}
public void DisplayTotals(int i)
{
////Read invoice qty from grid view 2
string invoice = GridView2.Rows[i].Cells[5].Text;
decimal invoiceTotal = Convert.ToDecimal(txtInvoiceTotal.Text) - Convert.ToDecimal(invoice);
txtInvoiceTotal.Text = invoiceTotal.ToString();
////Read invoice weight from grid view 2
string weight = GridView2.Rows[i].Cells[6].Text();
decimal invoiceWeight = Convert.ToDecimal(txtQtyWeight.Text) - Convert.ToDecimal(weight);
txtQtyWeight.Text = invoiceWeight.ToString();
}
public void DisplaySuccess(string message)
{
lblError.ForeColor = Color.Green;
lblError.Text = message;
}
public void DisplayError(string message)
{
lblError.ForeColor = Color.Red;
lblError.Text = message;
}
A few things to note:
You don't need to call Dispose() if you are using using.
You should always catch the most specific exception possible, per Microsoft's guidance. My example does this.
The exception handling for the primary key error is isolated into the method that calls the stored procedure. The overall business logic shouldn't have to know details about the SQL implementation. I've shown how you can identify the specific error based on this post.
Because there are four possible outcomes, I added an enumeration called TransactionResult so we could return the status to the caller easily.
Some of these methods are short-- just two lines-- and that is OK. The main reason to separate them out is to give them a meaningful name and make the code shorter and easier to read.
This code is much more structured but it could still be improved! In many implementations, the code that accesses the database is actually moved to a completely different layer or project.
See if this works. Moved your if/else together:
protected void Button2_Click(object sender, EventArgs e)
{
try
{
for (int i = GridView2.Rows.Count - 1; i >= 0; i--)
{
var row = GridView2.Rows[i];
CheckBox chk = row.FindControl("chkInvoice") as CheckBox;
if (chk != null && chk.Checked)
{
string strSQLconstring = System.Configuration.ConfigurationManager.ConnectionStrings["TWCL_OPERATIONSConnectionString"].ToString();
using (SqlConnection objConnection = new SqlConnection(strSQLconstring))
{
objConnection.Open();
using (SqlTransaction transaction = objConnection.BeginTransaction())
{
string SID = GridView2.Rows[i].Cells[3].Text.Trim();
SqlDataReader myReader = null;
using (SqlCommand command = new SqlCommand("PP_SelectStatus", objConnection, transaction))
{
command.CommandType = CommandType.StoredProcedure;
command.Parameters.AddWithValue("#invoiceNum", SID);
command.Parameters.AddWithValue("#custPONum", GridView2.Rows[i].Cells[4].Text.Trim());
myReader = command.ExecuteReader();
if (myReader.Read())
{
string invoice1 = (myReader["status"].ToString());
if (invoice1 == "0")
{
ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('This invoice num was already dispatched!')", true);
}
else if (invoice1 == "1")
{
using (SqlCommand cmd = new SqlCommand("PP_RemoveInvoice", objConnection, transaction))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#loadSheetNum", txtDispatchNum.Text);
cmd.Parameters.AddWithValue("#invoiceNum", SID);
cmd.Parameters.AddWithValue("#removeUser", lblUsername.Text.Replace("Welcome", ""));
int a = cmd.ExecuteNonQuery();
cmd.Dispose();
if (a > 0)
{
dt.Rows.RemoveAt(i);
////Read invoice qty from grid view 2
string invoice = GridView2.Rows[i].Cells[5].Text.ToString();
decimal invoiceTotal = Convert.ToDecimal(txtInvoiceTotal.Text) - Convert.ToDecimal(invoice);
txtInvoiceTotal.Text = invoiceTotal.ToString();
////Read invoice weight from grid view 2
string weight = GridView2.Rows[i].Cells[6].Text.ToString();
decimal invoiceWeight = Convert.ToDecimal(txtQtyWeight.Text) - Convert.ToDecimal(weight);
txtQtyWeight.Text = invoiceWeight.ToString();
lblError.ForeColor = Color.Green;
lblError.Text = "Selected record(s) successfully updated";
}
else
{
lblError.ForeColor = Color.Red;
lblError.Text = " Record has not yet been recorded";
}
}
//objConnection.Close();
transaction.Commit();
}
}
}
GridView2.DataSource = dt;
GridView2.DataBind();
txtInvoiceCount.Text = dt.Rows.Count.ToString();
}
}
}
}
}
catch (Exception ex)
{
if (ex.Message.StartsWith("Violation of PRIMARY KEY constraint"))
{
lblError.ForeColor = Color.Red;
lblError.Text = " This invoice number was remove from dispatch sheet before!!";
}
else
{
// re-throw the error if you haven't handled it
lblError.Text = ex.Message;
throw;
}
}
}
}
I have looked into all the questions on the "database is locked" exception but none solve my problem. I have a static function in DBActions class that inserts a record in DB as follows:
public static class DBActions
{
// save col, value pairs in DB table
public static int SaveInDB(string table, string[] cols, object[] vals)
{
int resultID = 0;
string query = $"insert into {table} (";
for (int i = 0; i < cols.Length - 1; i++)
{ // leave the last column coz comma does not follow it
query += cols[i] + ", ";
}
query += cols[cols.Length - 1] + ") values (";
for (int i = 0; i < cols.Length - 1; i++)
{
query += $"'{vals[i]}', ";
}
query += $"'{vals[vals.Length - 1]}')";
//MessageBox.Show(query);
using (SQLiteConnection con = new SQLiteConnection(Global.ConnectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(con))
{
try
{
con.Open();
using (SQLiteTransaction trans = con.BeginTransaction())
{
cmd.CommandText = query;
cmd.ExecuteNonQuery();
resultID = (int)con.LastInsertRowId;
trans.Commit(); // raises the exception
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
finally
{
con.Close();
cmd.Dispose();
}
}
}
return resultID;
}
}
and I am calling this static function whenever I need to save some record in any table like this:
Global.StartTime = GetCurrentTimeStamp();
string[] cols = { "SampleID", "OperatorID", "StartTimeStamp"};
object[] vals = { SampleID, CurrentUser, Global.StartTime};
Global.ExpID = DBActions.SaveInDB("ExperimentSettings", cols, vals);
When I call it the very first time, it throws the "database is locked" exception. For all others, it executes fine. What could be the possible cause of this? I think all my DB objects are properly being disposed off due to the using statements.
My requirement I inserted successfully I want to bind last increment id to the root folder file name.id was automatic incremented in SQL. I want to bind last incremented id on that bold part place.
This is my code please help me to solve this problem:
string insert = "insert into Articles values('" + html+ "','" + text + "')";
try
{
con.Open();
SqlCommand cmd = new SqlCommand(insert, con);
int i = cmd.ExecuteNonQuery();
if (i > 0)
{
using (StreamWriter file = new StreamWriter(System.Web.Hosting.HostingEnvironment.MapPath(#"~\Articles\**ID**.html"), true))
{
file.WriteLine(value.editor); // Write the file.
}
return msg;
}
else
{
return msg1;
}
}
catch (Exception ex)
{
}
finally
{
con.Close();
}
Please note that your code is a security risk as it's vulnerable to sql injection attacks as Sean Lange rightfully wrote in the comments.
Also, the empty catch is a problem as he pointed out. Do yourself a favor and never ever use empty catch blocks.
To get the last generated identity value in the current session you should use Sql Server's SCOPE_IDENTITY() function.
Note that if you have an instead of insert trigger on the table SCOPE_IDENTITY() will not give you the correct value.
Your code should look something like this:
string insert = "insert into Articles values(#html, #text); select scope_identity()";
using (var con = new SqlConnection("<YOUR CONNECTION STRING HERE>"))
{
using (var cmd = new SqlCommand(insert, con))
{
cmd.Parameters.Add("#html", SqlDbType.NVarChar).Value = html;
cmd.Parameters.Add("#text", SqlDbType.NVarChar).Value = text;
try
{
con.Open();
var databaseId = cmd.ExecuteScalar();
if (databaseId is int)
{
using (StreamWriter file = new StreamWriter(System.Web.Hosting.HostingEnvironment.MapPath(string.Format(#"~\Articles\{0}.html", databaseId)), true))
{
file.WriteLine(value.editor); // Write the file.
}
return msg;
}
else
{
return msg1;
}
}
catch (Exception ex)
{
// Write to log, show an error message to the user
}
}
}
I have an exception that Datatype mismatch in this line
byte[] _data = (byte[])row.getBlobBytes(1);
and in the table I have the type of column 2 is BLOB.
public static UrlRsc getContentUrl(String name) {
UrlRsc elementRsc = null;
try {
Statement statement = DB
.createStatement("SELECT * FROM table where"
+ " Name='"
+ name + "'");
statement.prepare();
Cursor cursor = statement.getCursor();
Row row;
while (cursor.next()) {
row = cursor.getRow();
byte[]_data;
_data = row.getBlobBytes(1);
}
statement.close();
cursor.close();
} catch (DatabaseException dbe) {
System.out.println(dbe.toString());
} catch (DataTypeException dte) {
System.out.println(dte.toString());
}
return elementRsc;
}
Can any one help me ?
Hi i am using following code for save image in my local database and i got success. i just posted my 3 methods
Note: When i am inserting image into data base i changed that image in byte array then only i can save into that table
1)Table creation 2) table insertion 3)image retrieving from table
ContactImage_table creation
public ContactImageTableCreation(){
try{
Statement stmt=DATABASE.createStatement("create table if not exists 'ContactImage_table'(ID 'TEXT',image 'blob',NodeId 'TEXT')");
stmt.prepare();
stmt.execute();
stmt.close();
}catch(Exception e){
System.out.println(e.getMessage());
}
}
Insert data into ContactImage_table
public void ContactImageTableInsertion(){
try{
Statement st=DATABASE.createStatement("insert into ContactImage_table (ID,Image,NodeId)values(?,?,?)");
st.prepare();
st.bind(1, "101");
st.bind(2, BYTE_ARRY);
st.bind(3,"103");
st.execute();
st.close();
}catch (Exception e) {
System.out.println(e.getMessage());
}
}
Retrieving data from ContactImage_table
public ContactImageTableDataRetriving(){
try{
Statement st=DATABASE.createStatement("select * from ContactImage_table");
st.prepare();
Cursor c=st.getCursor();
Row r;
int i=0;
while(c.next()){
r=c.getRow();
i++;
// ContactImageObject is a wrapper class for data handling
contactImageObj=new ContactImageObject();
contactImageObj.setId(r.getString(0));
byte[] decoded=r.getBlobBytes(1);
EncodedImage fullImage = EncodedImage.createEncodedImage(decoded, 0, decoded.length);
Bitmap b=fullImage.getBitmap();
contactImageObj.setImage(b);
// System.out.println("Successfully retrived");
if(i==0){
// System.out.println("No Records");
}
}
st.close();
}catch (Exception e) {
// System.out.println(e.getMessage());
}
}
just cross check your code with this code snippet hope you will get resolve all the best