Question

How can we handle the SELECT statement if we don’t know the column_names

with my little experience if i have the following query

 SELECT * FROM emp 

i would do

    While sqlReader.Read()
        Dim name as string = sqlReader.Item("emp_name")
    End While

Question

but what if i don’t know the number and columns names of what i’m getting
is there is any method of handling this
a method that tell us that there is x number of columns selected and their names

and then return this as a list of string , i don’t know if this is important or not but i’m doing this as a web service

Answer 1

You can use the FieldCount property of System.Data.SqlClient.SqlDataReader to get the number of fields. You can then use the GetName property to get the field names.

Dim Names as New list(of String) 
For i as integer = 0 to sqlReader.FieldCount -1 
    Names.Add(sqlReader.GetName(i))
Next

http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.aspx