I'm looking for a reference that nicely explains the different kinds of

joins, including Inner and Outer, left inner, left outer, etc. etc.   Does

anyone know of one in particular?



Cory

Inner Join produces a table which contains only those records from both

tables where the values in the joined upon column match - this is the usual

join that you do:



SELECT table1.field1, table2.field1

FROM table1, table2

WHERE table1.field1 = table2.field1



OR



SELECT table1.field1, table2.field1

FROM table1

INNER JOIN table2

ON table1.field1 = table2.field1



Outer Joins can be Left Outer Joins, Right Outer Joins, or Full Outer Joins.



An outer join finds all those records that an inner join does, plus records

from either the left, right, or both tables that do not have matches in the

joined upon column.



eg

SELECT table1.field1, table2.field1

FROM table1

LEFT JOIN table2

ON table1.field1 = table2.field1



would select all records from Table1, and only those records from Table2

where, in table2.field1 there was a corresponding value in table1.field1.

For those records in table1.field1 where there is no matching value in

table2.field1, the table2 column is filled with NULLs.



The reverse happens with Right Joins (table1 and table2 are juxtaposed).



Outer Joins find all records in all tables that are joined, subject to any

WHERE clause.



HTH



Cheers

Ken









----- Original Message -----

From: "Cory Koski" 

To: "ASP Databases" <asp_databases@p...>

Sent: Wednesday, June 14, 2000 12:57 AM

Subject: [asp_databases] SQL Join reference?





> I'm looking for a reference that nicely explains the different kinds of

> joins, including Inner and Outer, left inner, left outer, etc. etc.   Does

> anyone know of one in particular?

>

> Cory

thanks... wow...  didn't expect that, but that's great!  Thanks Ken!

----- Original Message -----

From: "Ken Schaefer" 

To: "ASP Databases" <asp_databases@p...>

Sent: Wednesday, June 14, 2000 1:41 AM

Subject: [asp_databases] Re: SQL Join reference?