schema-manager.txt

A Schema Manager instance helps you with the abstraction of the generation of SQL assets such as Tables, Sequences, Foreign Keys and Indexes.

To retrieve the `SchemaManager` for your connection you can use the `getSchemaManager()` method:

    [php]
    $sm = $conn->getSchemaManager();

Now with the `SchemaManager` instance in `$em` you can use the available methods to learn about your database schema:

++ listDatabases()

Retrieve an array of databases on the configured connection:

    [php]
    $databases = $sm->listDatabases();

++ listSequences($database = null)

Retrieve an array of `Doctrine\DBAL\Schema\Sequence` instances that exist for a database:

    [php]
    $sequences = $sm->listSequences();

Or if you want to manually specify a database name:

    [php]
    $sequences = $sm->listSequences('dbname');

Now you can loop over the array inspecting each sequence object:

    [php]
    foreach ($sequences as $sequence) {
        echo $sequence->getName() . "\n";
    }

++ listTableColumns($tableName)

Retrieve an array of `Doctrine\DBAL\Schema\Column` instances that exist for the given table:

    [php]
    $columns = $sm->listTableColumns('user');

Now you can loop over the array inspecting each column object:

    [php]
    foreach ($columns as $column) {
        echo $column->getName() . ': ' . $column->getType() . "\n";
    }

++ listTableDetails($tableName)

Retrieve a single `Doctrine\DBAL\Schema\Table` instance that encapsulates all the details of the given table:

    [php]
    $table = $sm->listTableDetails('user');

Now you can call methods on the table to manipulate the in memory schema for that table. For example we can add a new column:

    [php]
    $table->addColumn('email_address', 'string');

++ listTableForeignKeys($tableName)

Retrieve an array of `Doctrine\DBAL\Schema\ForeignKeyConstraint` instances that exist for the given table:

    [php]
    $foreignKeys = $sm->listTableForeignKeys('user');

Now you can loop over the array inspecting each foreign key object:

    [php]
    foreach ($foreignKeys as $foreignKey) {
        echo $foreignKey->getName() . ': ' . $foreignKey->getLocalTableName() ."\n";
    }

++ listTableIndexes($tableName)

Retrieve an array of `Doctrine\DBAL\Schema\Index` instances that exist for the given table:

    [php]
    $indexes = $sm->listTableIndexes('user');

Now you can loop over the array inspecting each index object:

    [php]
    foreach ($indexes as $index) {
        echo $index->getName() . ': ' . ($index->isUnique() ? 'unique' : 'not unique') . "\n";
    }

++ listTables()

Retrieve an array of `Doctrine\DBAL\Schema\Table` instances that exist in the connections database:

    [php]
    $tables = $sm->listTables();

Each `Doctrine\DBAl\Schema\Table` instance is populated with information provided by all the above methods. So it encapsulates an array of `Doctrine\DBAL\Schema\Column` instances that can be retrieved with the `getColumns()` method:

    [php]
    foreach ($tables as $table) {
      echo $table->getName() . " columns:\n\n";
      foreach ($table->getColumns() as $column) {
        echo ' - ' . $column->getName() . "\n";
      }
    }


++ listViews()

Retrieve an array of `Doctrine\DBAL\Schema\View` instances that exist in the connections database:

    [php]
    $views = $sm->listViews();

Now you can loop over the array inspecting each view object:

    [php]
    foreach ($views as $view) {
        echo $view->getName() . ': ' . $view->getSql() . "\n";
    }

++ createSchema()

For a complete representation of the current database you can use the `createSchema()` method which returns an instance of `Doctrine\DBAL\Schema\Schema`, which you can use in conjunction with the SchemaTool or Schema Comparator.

    [php]
    $fromSchema = $sm->createSchema();

Now we can clone the `$fromSchema` to `$toSchema` and drop a table:

    [php]
    $toSchema = clone $fromSchema;
    $toSchema->dropTable('user');

Now we can compare the two schema instances in order to calculate the differences between them and return the sql required to make the changes on the database:

    [php]
    $sql = $fromSchema->getMigrateToSql($toSchema, $conn->getDatabasePlatform());

The `$sql` array should give you a sql query to drop the user table:

    [php]
    print_r($sql);

    /*
    array(
      0 => 'DROP TABLE user'
    )
    */