how to subtract a value from database with a value from text

Question

i'm using vb.net and trying to figure out how to write a sql command to subtract a value from database with a value enter by the user from a textbox?

Amitesh Verma · Answer

string txtvalue=txtbox.text; string query=Select amount from table; datatable dt=new datatable; after this get the amount value in string newamount=dt.rows[0][amount].tostring(); now subtract: string subtractdata=txtvalue-newamount;

Rajeesh Menoth · Answer

Hi Private Sub TextBox6_TextChanged(ByVal sender As System.Object ByVal e As System.EventArgs) Handles TextBox6.TextChanged Dim value1 value2 As Integer If Integer.TryParse(TextBox1.Text value1) Then If Integer.TryParse(TextBox6.Text value2) Then TextBox11.Text = (value1 - value2).ToString() End If End If End Sub Ref : https://social.msdn.microsoft.com/Forums/en-US/db46cc77-2d38-4b2e-b0a2-2a364686c291/subtract-two-value-intextboxs?forum=vblanguage

Amitesh Verma · Answer

yab fine with that you can use this like this select columnname from table where condtioncolumn='+textbox1.text+';

Rajeesh Menoth · Answer

Hi Welcome King Umar :) Correct one.. Use + don't use & select Quantity FROM [AddItem] WHERE = ' + TextBox1.Text +  '

King Umar · Answer

okay (Y) :D

King Umar · Answer

thanks a lot Amitesh and Rajeesh i have another question how if i want to specified the sql commandfor example i put a 'WHERE' condition on the sql command like select Quantity FROM [AddItem] WHERE =' & TextBox1.Text &  '  is this are correct or not ?