Question

Whenever I have

Dim catID as integer

And I use this in a query like this:

cmd.CommandText = "select * from categories where parentid='" + catID + "'"

I get:

Conversion from string select * from categories where p to type Double is not valid.

Why is it so?
The parentid datatype in sql is integer.

Answer 1

Try

cmd.CommandText = string.Format("select * from categories where parentid='{0}'", catID)

if parentid is a numeric field in your database then you’ll need

cmd.CommandText = string.Format("select * from categories where parentid={0}", catID)