MS Access SELECT查询DatePart

Question

i have some problem with my SELECT Query to MS Access .mdb file.

i am using VB.Net and have to send query like..

"SELECT d_date, d_tons, d_qty, d_cost FROM [deal] WHERE DatePart(""m"", [d_date]) = '" _
+ DTP.Value.Month.ToString + "' AND ([d_client] = '" + cBoxClient.Text + "')"

But it doesn't work.. No Error in compiling but this Query cannot SELECT any data.

DTP is DateTimePicker, i select Month with DTP and filled some text into cBoxClient(ComboBox)

What's wrong with that Query? i have no idea because i always used MySQL and this is my first application development with MS Access..

Please HELP me.

Answer 1

Use parameterized query, that will save you from sql injection and complexity of converting specific data format (such as DateTime ) to it's string representation that is valid according to database specific culture. For example :

Dim queryString = "SELECT d_date, d_tons, d_qty, d_cost FROM [deal] WHERE " & _ 
                  "DatePart(""m"", [d_date]) = ? AND ([d_client] = ?)"
OleDbCommand cmd = New OleDbCommand(queryString, connection)
cmd.Parameters.AddWithValue("@date", DTP.Value.Month)
cmd.Parameters.AddWithValue("@client", cBoxClient.Text)