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 command,for example i put a 'WHERE' condition on the sql command like "select Quantity FROM [AddItem] WHERE ='" & TextBox1.Text & " ' " is this are correct or not ?

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

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Answers (6)