Java Reference
In-Depth Information
Listing 2.1
A sample SQL mapping descriptor
<select id="getAddress"
parameterClass="int"
resultClass="Address">
SELECT
ADR_ID as id,
ADR_DESCRIPTION as description,
ADR_STREET as street,
ADR_CITY as city,
ADR_PROVINCE as province,
ADR_POSTAL_CODE as postalCode
FROM ADDRESS
WHERE ADR_ID = #id#
</select>
Here we can see a
SQL
SELECT
statement that returns address data. From the
<select>
element we can see that it takes an Integer object as a parameter, which
is marked by the
#id#
token in the
WHERE
clause. We can also see that the result is
an object instance of the
Address
class, which is assumed to contain the properties
of the same name as the aliases assigned to each column in the
SELECT
clause. For
example, the alias
id
would be mapped to a property of the
Address
class also
called
id
.
Believe it or not, that is all it takes to map a
SQL
statement that receives
an integer as a parameter and returns an
Address
object as output. The Java code
used to execute this statement would be
Address address = (Address) sqlMap.queryForObject("getAddress",
new Integer(5));
The
SQL
mapping approach is a very portable concept that can be applied to any
full-featured programming language. For example, the C# code from i
BATIS
.
NET
is nearly identical:
Address address = (Address) sqlMap.QueryForObject("getAddress", 5);
Of course there are more advanced options for mapping, especially around
results. But we'll discuss those in greater detail in part 2, “i
BATIS
basics.” Right
now, it's more important to understand the features and benefits of i
BATIS
and
how it works.
