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ASP.NET(vb.net) & Try Catch Exception The try-catch statement consists of a try block followed by one or more catch clauses, which specify handlers for different exceptions. When an exception is thrown, the common language runtime (CLR) looks for the catch statement that handles this exception. If the currently executing method does not contain such a catch block, the CLR looks at the method that called the current method, and so on up the call stack. If no catch block is found, then the CLR displays an unhandled exception message to the user and stops execution of the program.

ShotDev Focus:
- Try Catch Exception Statement

Try
'*** Code & Command ***'
Catch ex As Exception
'*** Event Error ***'
Finally
'*** (Option) Event Completed Status ***'
End Try

Example

Dim objConn As System.Data.OleDb.OleDbConnection
Dim objCmd As System.Data.OleDb.OleDbCommand
Dim strConnString,strSQL As String
Dim Trans As OleDbTransaction

strConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="&Server.MapPath("database/mydatabase.mdb")&";Jet OLEDB:Database Password=;"
objConn = New System.Data.OleDb.OleDbConnection(strConnString)
objConn.Open()

'*** Start Transaction ***'
Trans = objConn.BeginTransaction(IsolationLevel.ReadCommitted)

Try

'*** Query 1 ***'
strSQL = "INSERT INTO customer (CustomerID,Name,Email,CountryCode,Budget,Used) " & _
"VALUES ('C005','Weerachai Nukitram','webmaster@shotdev.com','TH','2000000','1000000')"
objCmd = New System.Data.OleDb.OleDbCommand()
With objCmd
.Connection = objConn
.Transaction = Trans
.CommandType = CommandType.Text
.CommandText = strSQL
End With
objCmd.ExecuteNonQuery()

'*** Query 2 ***'
strSQL = "INSERT INTO customer (CustomerID,Name,Email,CountryCode,Budget,Used) " & _
"VALUES ('C005','Weerachai Nukitram','webmaster@shotdev.com','TH','2000000','1000000')"
objCmd = New System.Data.OleDb.OleDbCommand()
With objCmd
.Connection = objConn
.Transaction = Trans
.CommandType = CommandType.Text
.CommandText = strSQL
End With
objCmd.ExecuteNonQuery()

Trans.Commit() '*** Commit Transaction ***'
Me.lblText.Text = "Record is commit"

Catch ex As Exception
Trans.Rollback() '*** RollBack Transaction ***'

Me.lblText.Text = "Record is rollback ("& ex.Message &")"
End Try

objCmd = Nothing
objConn.Close()
objConn = Nothing

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Category: ASP.NET(vb.net) & Syntax by admin