Operation Manual

Understanding Databases
Linking tables
25
Crystal Reports User’s Guide 503
Note: Left Outer and Right Outer joins are handled differently in the SQL
language from other join types. If the database is accessed through ODBC,
Crystal Reports uses ODBC syntax in the SQL statement. If you are
connecting to a SQL database directly (not through ODBC), Crystal Reports
uses a syntax native to the database. For more information about what an
Outer join looks like in an SQL statement, refer to Microsoft ODBC
documentation or to the documentation for your SQL database.
Full Outer join
A Full Outer join is a bidirectional outer join where you can see all records in
your linked tables. The result set from a Full Outer join includes all the records
in which the linked field value in both tables is an exact match. It also includes
a row for every record in the primary (left) table for which the linked field value
has no match in the lookup table, and a row for every record in the lookup
(right) table for which the linked field value has no match in the primary table.
If you link the Customer table to the Orders table, you get one row in the table
for each order a customer has placed. You also get a row for every order
found that cannot be linked to a customer, and a row for every customer for
whom an order cannot be found.
58 20 1956.20
60 16 24580.50
62 19 7911.80
63 28 19766.20
63 32 12763.95
64 14 8233.50
25 10320.87
Customer Table Orders Table Orders Table
Customer ID Order ID Order Amount
Customer Table Orders Table Orders Table
Customer ID Order ID Order Amount
52 6 25141.50
53 11 19164.30
53 21 1683.60
57 4 15716.40
58 20 1956.20