Execute Reader..
1.Returns a datareader with data.
2.It is done by command object.
3.It is readonly.
4.It executes only select command.
5. This is known as a forward-only retrieval of records.It uses your sql statement to read through the table from the first to the last.
Execute NonQuery..
1.It will not return any data.
2.It is used with insert and update.
3.It returns only the number of rows affected.
Execute Scaler..
1.It returns only one value.
2.That value will the first column first row value.
Execute Query..
1.Its for command objects.
2.It returns the value given by database through select statement.
Excute Reader:
Run a Query Command or a Stored procedure that selects records.
Excute Reader return one or more resultes.
con.open()
dim dr as sqldatareader()
cmd.excutereader()
'Result here
con.close()
U can access the selected records using the SqlDataReader object and use the Read to loop through them.you move the next result using next results method.
Excute NonQuery:-
un a Query Command or a Stored procedure that affects the specified table.This means anything but a query command. You normally use this method to issue an INSERT, UPDATE, DELETE, CREATE, and SET statement.
Con.Open()
nRecsAffected = cmd.ExecuteNonQuery();
Con.Close();
' check the record(s) affected here
ExecuteScalar:-
ExecuteScalar Expects to run a query command or more likely a stored procedure that returns data.However,This method is different from ExecuteReader in that it just makes available, as a scalar value,
the first column on the first row of the selected resultset.
c
Connection.Open();
Object o = cmd.ExecuteScalar(); cmd.Connection.Close();
// work on the scalar here
The method returns the value as a boxed object.
1.Returns a datareader with data.
2.It is done by command object.
3.It is readonly.
4.It executes only select command.
5. This is known as a forward-only retrieval of records.It uses your sql statement to read through the table from the first to the last.
Execute NonQuery..
1.It will not return any data.
2.It is used with insert and update.
3.It returns only the number of rows affected.
Execute Scaler..
1.It returns only one value.
2.That value will the first column first row value.
Execute Query..
1.Its for command objects.
2.It returns the value given by database through select statement.
Excute Reader:
Run a Query Command or a Stored procedure that selects records.
Excute Reader return one or more resultes.
con.open()
dim dr as sqldatareader()
cmd.excutereader()
'Result here
con.close()
U can access the selected records using the SqlDataReader object and use the Read to loop through them.you move the next result using next results method.
Excute NonQuery:-
un a Query Command or a Stored procedure that affects the specified table.This means anything but a query command. You normally use this method to issue an INSERT, UPDATE, DELETE, CREATE, and SET statement.
Con.Open()
nRecsAffected = cmd.ExecuteNonQuery();
Con.Close();
' check the record(s) affected here
ExecuteScalar:-
ExecuteScalar Expects to run a query command or more likely a stored procedure that returns data.However,This method is different from ExecuteReader in that it just makes available, as a scalar value,
the first column on the first row of the selected resultset.
c
Connection.Open();
Object o = cmd.ExecuteScalar(); cmd.Connection.Close();
// work on the scalar here
The method returns the value as a boxed object.
| Command | Purpose |
| ExecuteReader | Returns a connected recordset. It is forward only and uneditable at the same time. cmd.CommandText = "select deptno, dname, loc from dept"; Dim dr As sqlDataReader = cmd.ExecuteReader While dr.Read ' Process data as you would normally. End While |
| ExecuteScalar | This returns one value only, no recordsets. cmd.CommandText = "Select Name, DOB, from Emp where ID=1"; Dim strName As string = cmd.ExecuteScalar.ToString |
| ExecuteXMLReader | Returns the recordset as a XML document. cmd.CommandText = "select deptno, dname, loc from dept"; cmd.CommandText = "Select Name, DOB, Town from Emp FOR XML AUTO, ELEMENTS"; Dim strName As string = cmd.ExecuteScalar.ToString dim reader as System.XML.XMLReader = cmd.ExecuteXMLReader Do While objXML.Read ' Do Some processing Loop objXML.Close con.Close |
| ExecuteNonQuery | Doesn't return any recordsets, ideal for insert, update and delete queries where no recordsets are returned. cmd.CommandText = "Delete from Class where PupilHasLeft=true"; cmd.ExecuteNonQuery However, although records are returned, the number of affected records is. |
| da.Fill(DT) | This populates a datatable or dataset from a select query. Dim dataAdapter As System.Data.IDbDataAdapter = New System.Data.SqlClient.SqlDataAdapter Dim dataSet As System.Data.DataTable = New System.Data.DataTable dataAdapter.SelectCommand = dbCommand dataAdapter.Fill(dataTable) For Each objDR in objDT.Rows ' Do Some Processing Next |
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