sql datahandling with vb.net update command

Question

Hi Friend I Have a SqlDataBase in Which It Have Three Fields Namely **" mc , amount , customername

"** Now I am Update this Fileds Using Upadte command In vb.net Form now Wat I Need is I Want To Add

This New Value While Updating With the Previous Value

     cmd.CommandText = " UPDATE mc SET mc =  " & TextBox3.Text & " , amount =  " & TextBox13.Text & " WHERE customername =  " & " '" & ST & "'" & " "

Also I have A Problem As my Amount column Is not Being Updated

For Example Now Let us Consider

This is Form Data To be Updated to the mc table

Textbox3.text = 600 //sent to mc table to the field name mc

Textbox13.text = 10000 //sent to mc table to the filed name amount

customer name = Rajesh // mc table customername Which To be Updated

Now the mc Table already have the values for customername Rajesh as mc = 500 amount =1250

Now My Problem is Want to Update the Field but I Want to SUM the values of old With The New one and show as for Rajesh IT should show as

mc = 1100 //since 600+500 amount = 11250 //since 10000+1250 I Think You Can Understand Now

Plz Send me how to Change this Code According So That I Could Get The Value as Like That

Answer 1

You probably want to do something like this then:

cmd.CommandText = " UPDATE mc SET mc = mc + " & TextBox3.Text & " , amount = amount + " & TextBox13.Text & " WHERE customername =  " & " '" & ST & "'" & " "

I would suggest using string.Format here though. It looks a lot cleaner.

cmd.CommandText = string.Format("UPDATE mc SET mc = mc + {0}, amount = amount + {1} WHERE customername = '{2}'", TextBox3.Text, TextBox13.Text, ST)

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