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Updating the Database
4:13Now that we have our first migration created, let's see how to update our database.
Now we're ready to update our database.
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Well, since we don't have
an existing database,
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updating our database will cause
code first migrations to create it.
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To update our database,
we'll open the Package Manager Console and
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run the update database command.
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Update-database and press Enter.
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Okay, the command completed successfully.
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If we open
the SQL Server Object Explorer window,
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we can see our new
ComicBookGalleryMigrations database.
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The name in the database is being set
using the database connection string
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defined in the project's app.config file.
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We can also expand the Tables folder
to see the list of our tables.
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We can use the verbose flag to see the SQL
statements that code first migrations is
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running to create our database.
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To test this,
let's first delete our database.
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Then rerun the update database
command with the verbose flag.
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Update-database -verbose.
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And press Enter.
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Once the command has completed, let's
scroll up through the console output.
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Okay, here's where our migration starts.
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Here are the CREATE TABLE SQL statements
for the Artist and ComicBookArtist tables.
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Followed by the CREATE INDEX SQL
statements to create the indexes on
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the ComicBookArtist table.
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And here are the statements for
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the ComicBook series and Role tables.
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Once all of the tables were created,
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then the ALTER TABLE SQL statements
to create the foreign keys were ran.
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The last of the statements that were
ran were to create the MigrationHistory
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table and insert a row into that table for
this migration.
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The MigrationHistory table is used
to track which migrations have
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been applied to the database.
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When you run the update database command,
any migrations contained in your project
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that don't have an associated row in this
table will get applied to the database.
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The Model column contains
a serialized version of the EDMX for
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your entity data model.
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That's what this long string of
letters and numbers represents.
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As an aside,
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it's possible to decode the Model
column value in order to see the EDMX.
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See the teacher's notes for
more information.
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Now that you've seen how to use the update
database command to update your local
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database, you might be wondering how
to do this in other environments,
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like on a test or production server.
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We'll take a look at deployment
options in the next section.
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Let's run our application and
make sure that things work as expected.
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Open the Program.cs file,
set a break point on the query that
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retrieves the list of comic books and
run the application.
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Okay, we'll add our break point.
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Press F10 to execute the query and
continue to the next statement.
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If we hover over the ComicBooks variable,
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we can see that
the collections count is zero.
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Well, this makes sense.
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While we created our database,
our migration didn't include any C data.
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Let's see how to fix that next.
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