How to create join in Database Manager?

go out and buy SQL for Dummies.

Join Fundamentals

basically:

say what you want to get out of the tables

Say which tables you want the information from

Say how the tables relate to each other [On clause]

Say how you want to restrict the result set Further [Where]

select
I.IfName as Interface
,IP.IPAddress as 'IP Address'
,N.Caption
from NodesData N
INNER JOIN Interfaces I
on N.Nodeid=I.Nodeid
INNER JOIN NodeIPAddresses IP
on N.NodeID=IP.NodeiD
and I.Interfaceindex=IP.InterfaceIndex

Richard, thanks!   This works great!

So, the letters are table aliases?  Like I.IfName?

From Join Fundamentals,

When a column name is not duplicated in two or more tables used in the query, references to it do not have to be qualified with the table name. This is shown in the previous example. Such a SELECT statement is sometimes difficult to understand because there is nothing to indicate the table that provided each column. The readability of the query is improved if all columns are qualified with their table names. The readability is further improved if table aliases are used, especially when the table names themselves must be qualified with the database and owner names. The following is the same example, except that table aliases have been assigned and the columns qualified with table aliases to improve readability:

Richard, thanks!   This works great!

So, the letters are table aliases?  Like I.IfName?

From Join Fundamentals,

When a column name is not duplicated in two or more tables used in the query, references to it do not have to be qualified with the table name. This is shown in the previous example. Such a SELECT statement is sometimes difficult to understand because there is nothing to indicate the table that provided each column. The readability of the query is improved if all columns are qualified with their table names. The readability is further improved if table aliases are used, especially when the table names themselves must be qualified with the database and owner names. The following is the same example, except that table aliases have been assigned and the columns qualified with table aliases to improve readability:

yes...

I like to use table aliases because it makes referring to specific values shorter and I am a poor typist

typically I use the initials of the table name, e.g. CPA, CPS, CP instead of CustomPollerAssignment, CustomPollerStatus, and CustomPoller.