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4. Manipulate and display the results (if a query) or check/show number of database
rows affected (for an update).
5. Repeat steps 4 and 5 as many times as required for further queries/updates.
6. Close the connection.
[If using an earlier version of JDBC, the following additional step is required
before those above: Load the database driver. ]
For purposes of illustration, we shall assume the existence of an MS Access
database called
Finances.accdb
that holds a single table called
Accounts
. The structure
of this simple table is as shown below.
Field name
MS access type
Java type
acctNum
Number
int
surname
Text
String
fi rstNames
Text
String
balance
Currency
fl oat
We shall further assume that the DSN given to the database is
Finances
.
Let's take each of the above seven steps in turn for this database…
1. Establish a Connection to the Database
We declare a
Connection
reference and call static method
getConnection
of class
DriverManager
to return a
Connection
object for this reference. Method
get-
Connection
takes three
String
arguments:
a URL-style address for the database;
a user name;
a password.
The JDBC API specifi cation recommends that the database address have the
following format:
jdbc:<sub-protocol>:<data-source>
Here,
<sub-protocol>
specifi es a database connection service (i.e., a
driver
) and
<data-source>
provides all the information needed by the service
to locate the database (typically, the URL path to the database). For a
local
ODBC
database with data source name
Finances
, the sub-protocol is
odbc
and the fi nal part
of the address is simply the name of the data source:
jdbc:odbc:Finances
Assuming that our
Finances
database is indeed local and that we did not set a
user name or password for this database, the line required to open a connection to
the database would be similar to this:
Connection connection =
DriverManager.getConnection(
"jdbc:odbc:Finances", "", "");
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