Doctrine has a very powerful abstraction of database schemas. It offers an object-oriented representation of a database schema with support for all the details of Tables, Sequences, Indexes and Foreign Keys. These Schema instances generate a representation that is equal for all the supported platforms. Internally this functionality is used by the ORM Schema Tool to offer you create, drop and update database schema methods from your Doctrine ORM Metadata model. Up to very specific functionality of your database system this allows you to generate SQL code that makes your Domain model work.
You will be pleased to hear, that Schema representation is completely decoupled from the Doctrine ORM though, that is you can also use it in any other project to implement database migrations or for SQL schema generation for any metadata model that your application has. You can easily generate a Schema, as a simple example shows:
<?php $schema = new \Doctrine\DBAL\Schema\Schema(); $myTable = $schema->createTable("my_table"); $myTable->addColumn("id", "integer", array("unsigned" => true)); $myTable->addColumn("username", "string", array("length" => 32)); $myTable->setPrimaryKey(array("id")); $myTable->addUniqueIndex(array("username")); $schema->createSequence("my_table_seq"); $myForeign = $schema->createTable("my_foreign"); $myForeign->addColumn("id", "integer"); $myForeign->addColumn("user_id", "integer"); $myForeign->addForeignKeyConstraint($myTable, array("user_id"), array("id"), array("onUpdate" => "CASCADE")); $queries = $schema->toSql($myPlatform); // get queries to create this schema. $dropSchema = $schema->toDropSql($myPlatform); // get queries to safely delete this schema.
Now if you want to compare this schema with another schema, you can
Comparator class to get instances of
ColumnDiff, as well as information about other
foreign key, sequence and index changes.
<?php $comparator = new \Doctrine\DBAL\Schema\Comparator(); $schemaDiff = $comparator->compare($fromSchema, $toSchema); $queries = $schemaDiff->toSql($myPlatform); // queries to get from one to another schema. $saveQueries = $schemaDiff->toSaveSql($myPlatform);
The Save Diff mode is a specific mode that prevents the deletion of tables and sequences that might occur when making a diff of your schema. This is often necessary when your target schema is not complete but only describes a subset of your application.
All methods that generate SQL queries for you make much effort to get the order of generation correct, so that no problems will ever occur with missing links of foreign keys.
A schema asset is considered any abstract atomic unit in a database such as schemas,
tables, indexes, but also sequences, columns and even identifiers.
The following chapter gives an overview of all available Doctrine 2
schema assets with short explanations on their context and usage.
All schema assets reside in the
This chapter is far from being completely documented.
Represents a table column in the database schema. A column consists of a name, a type, portable options, commonly supported options and vendors specific options.
The following options are considered to be fully portable across all database platforms:
- notnull (boolean): Whether the column is nullable or not. Defaults to
- default (integer|string): The default value of the column if no value was specified.
- autoincrement (boolean): Whether this column should use an autoincremented value if
no value was specified. Only applies to Doctrine's
biginttypes. Defaults to
- length (integer): The maximum length of the column. Only applies to Doctrine's
binarytypes. Defaults to
nulland is evaluated to
255in the platform.
- fixed (boolean): Whether a
binaryDoctrine type column has a fixed length. Defaults to
- precision (integer): The precision of a Doctrine
floattype column that determines the overall maximum number of digits to be stored (including scale). Defaults to
- scale (integer): The exact number of decimal digits to be stored in a Doctrine
floattype column. Defaults to
- customSchemaOptions (array): Additional options for the column that are supported by all vendors:
- unique (boolean): Whether to automatically add a unique constraint for the column.
The following options are not completely portable but are supported by most of the vendors:
- unsigned (boolean): Whether a
bigintDoctrine type column should allow unsigned values only. Supported by MySQL, SQL Anywhere and Drizzle. Defaults to
- comment (integer|string): The column comment. Supported by MySQL, PostgreSQL,
Oracle, SQL Server, SQL Anywhere and Drizzle. Defaults to
The following options are completely vendor specific and absolutely not portable:
- columnDefinition: The custom column declaration SQL snippet to use instead
of the generated SQL by Doctrine. Defaults to
null. This can useful to add vendor specific declaration information that is not evaluated by Doctrine (such as the
ZEROFILLattribute on MySQL).
- customSchemaOptions (array): Additional options for the column that are supported by some vendors but not portable:
- charset (string): The character set to use for the column. Currently only supported on MySQL and Drizzle.
- collation (string): The collation to use for the column. Supported by MySQL, PostgreSQL, Sqlite, SQL Server and Drizzle.
- check (string): The check constraint clause to add to the column.