Question : SQL Query [Multitables] in DataGridView

I am trying to execute SQL Query to get data from two tables, here is example:

Table1: Users { id, Username, GroupID }
Table 2: Groups { id, GroupName }

SQL Query: SELECT Users.Username,Groups.GroupName FROM Users,Groups WHERE Users.GroupID = Groups.id

This will show the columns Username and GroupName in data grid, this way will find group name for each group id, so the user will see the group name not the group id.

The Result in DataGridView
------------------------------------------------
Username                   GroupName
------------------------------------------------
User1                          GroupA
User2                          GroupA
User3                          GroupB
User4                          

In the above example User4 don't have group, in the table Users it have the Username: User4, GroupID: 0, The group id which is ZERO is not existed, so there is not group name available for User4.

The problem is if the user group id is not existed in "Groups" table the row will not appear in the result.
I want all the data to appear, if the group is not existed for the user id, it appear blank.

Answer : SQL Query [Multitables] in DataGridView

SELECT Users.Username,Groups.GroupName
FROM Users LEFT JOIN Groups ON Users.GroupID = Groups.id