Transcript Connecting to MySQL using Java

Connecting to MySQL using
Java
By:
– Required to use
Java.sql so that
we can use
Connection and
Queries using
strings.
– Javax.swing.*
needed for
components used
in GUI
– Java.io for input
and output
functions.
– Java.awt.* for
interactivity with
the GUI.
Connection class comes
from Java.sql.* library.
Used to establish a
connection with the
database and starts with
a null connection until
told to connect.
Connecting to the
database is enclosed
inside a try block to
catch exceptions in
connecting, so program
doesn’t crash and
problems can be fixed
later.
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ActionPerformed
grabs the actions from
buttons, and depending
on which button is
clicked, uses the
appropriate action.
There are only 2 types
of statements in SQL,
update type statements
and Query type
statements.
An Update statement
is used to modify the
database in some way.
Update is a simple
process, the function
returns an integer of
the number of columns
returned, or -1 if the
update failed.
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A query type statement
is used when we are
retrieving data from the
database
 A ResultSet, that
executeQuery returns,
is the data retrieved in
a 2 dimensional array
similar to the format of
a database.
 A ResultSet can
contain multiple data
types. In this case, it
cannot be accessed as a
normal 2 dimensional
array and we have to
use special get
functions to retrieve the
data.
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The amount of columns
returned by a query statement
cane be retrieved using the
functions of a
ResultSetMetaData., this
holds information about the
data returned. For example:
the name of the column, how
many columns, and the SQL
data type of the column.
 All data retrieved in this
program is used as strings to
be printed to the TextArea in
the GUI.
 If we wanted to actually use
the data for specific purposes,
there are other functions to
get the true data type, rather
than strings.
 Rs.next() points returns a true
if there is another row of data
in the 2 dimensional array. It
also move the ResultSet to
that row for retrieval with a
ResultSetMetaData data type.