Question

I have one table Metal_Master in that column having Opening_Weight I am updating value of that column by fetching previous value and aadding some value then again update that value .

My code for this is

ConnectionDB ReturnMWeight = new ConnectionDB("SELECT Opening_Weight FROM Metal_Master WHERE Metal_Name='GOLD';");
DataTable weighttd = ReturnMWeight.returntable();
GoldW = GoldW + Convert.ToDouble(weighttd.Rows[0][0].ToString());
ConnectionDB AddMWeight = new ConnectionDB("UPDATE Metal_Master SET Opening_Weight=" + GoldW + " WHERE Metal_Name='GOLD';");
AddMWeight.AddData();

But i want to directly update value in single query Please help ..

Answer 1

you can do the UPDATE directly without running select statement,

UPDATE Metal_Master 
SET Opening_Weight = Opening_Weight + new_Value
WHERE Metal_Name='GOLD'

for better quality of code,

• use using statement for proper objet disposal
• use try-catch for proper handling of unexpected exceptions.
• parameterized the query to prevent from sql injection