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Now that you've seen how to connect to and
interact with

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a database in Java using JDBC,
we're ready to take it to the next level.

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If we're writing a contact
manager application,

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one of the obvious objects we'd want
to work with would be a contact object.

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We can write a POJO.

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Remember, that's plain old Java object.

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That models a contact by creating a class
that includes an instance field for

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each of the database columns we define.

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Then, when we have a new contact object,

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we should be able to simply
save it to the database.

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Let's write a first draft of
what that might look like.

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What I'd like to do here is write a save
method that allows us to quickly save

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a contact to the database without having
to continually rewrite the SQL to do so.

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Let's get this started at the bottom.

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So I'll start by entering a method
stub here, public static void.

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I'll call it save.

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And I'd like to save a cCntact object so
I'll include that as a parameter.

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And let me drop a couple comments in here.

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The things that we'd like to do.

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So we'll start by composing the query,
and then we will execute the query.

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Let's begin composing the query by using
a String variable, I'll name it sql.

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And this variable will hold the general
syntax for an insert statement.

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We wanna insert it into
the contacts table.

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We'll list our column names, and

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then we'll list the actual
values that we'd like to insert.

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So my column names here are firstname,
lastname, email, and phone.

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And what I wanna do is stick placeholders
in here where I can put the actual

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values from my contact object for
the values of the insert statement.

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But, so that I don't forget the single
quotes that surround a string value in

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SQL, I'm gonna stick those in right now.

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The first three columns
are string columns.

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So for our first name we'll
have a string placeholder.

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Same for last name and email.

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And for the phone we'll
have a numeric placeholder.

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Now, let's take the actual values
of the Contact object's fields

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into this string using String.format.

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And I will place or assign that value
right back to the SQL variable.

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So I'll use string String.format.

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The sql variable holds my general format,
and

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then into the placeholders I will place
the values contact.getFirstName(),

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contact.getLastName(), contact.getEmail()
and

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contact.getPhone.

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If you wanna verify that those
getters actually exist are are in

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alignment with the Contact class,
go ahead and

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click on Contact.java to verify
that that is indeed the case.

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In order to execute this update
using statement.executeUpdate,

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we'll need that statement object.

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Let's include it as a parameter
after the Contact object.

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And I will just call this Statement.

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So under execute the query,
I can now call statement.executeUpdate.

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And pass it the value of the sql variable,

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which will hold our fully
formatted insert statement,

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including the values that have been
placed into these placeholders.

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Just one more issue with this method.

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The statement.executeUpdate method is
declared as throwing a SQL Exception.

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So, either we'll need a try
catch block right here,

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which catches the SQL exception.

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Or, we'll have to declare this save
method as throwing the SQL exception,

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which means that the caller of this
method will have to handle this.

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We'll choose this ladder approach,

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since the caller of this method
will be the main method up above.

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And up here in the main method we
already have a try catch that handles

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the SQL exception.

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So let's add that throws
clause right here.

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Throws, SQLException.

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Speaking of that main method, let's return
to that main method and replace these two

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insert statements with calls to
our newly coded save method.

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So the first I'll need to do
is create a Contact object

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with all the same information that's
included in this first insert statement.

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So the order of this, and again,

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you can verify this in
contact.java is first name,

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last name, email, and phone.

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I'm gonna just copy and paste this.

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But this is a long value, so
I won't forget to append the L there so

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the JVM knows to consider it a long.

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Now, I'm ready to call our
newly coded save method.

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So I'll save this contact using the
statement object that I constructed above.

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And we'll repeat all that for
James Gosling as well.

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We'll add him right here, James Gosling.

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James@java.com.

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And I'll use this phone number,
without forgetting the L.

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Now I should be able to delete these
two calls to the executeUpdate method.

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Let's compile and run our code to
see if we get the same results.

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javac JdbcMain.java.

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Looks like all compiles well.

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So, let's run it specifying the class
path that includes both the jar file and

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the current directory.

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Awesome!

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Same result as before.

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We've now abstracted away the actual
SQL for insert statements.

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So up above, instead of crafting
the actual SQL statements,

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we can simply call our save method and
it takes care of the details for us.

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Hey, great job!

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You've now used Java to connect to and
interact with a database.

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In addition, you've taken your first step
toward allowing the saving of POJOs.

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It's nice to be able to call a save method
with your POJO instead of having to craft

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and re-craft SQL statements
with every database change.

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You're well on your way to discovering
the next level of data management

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using application code.