Data Definition Language (DDL) commands

Data Definition Language (DDL) is a set of SQL statements to define the database structure.

DDL statements are used to create and change the database objects in a database. These objects can be tables, indexes, views, stored procedures, triggers, and so on.

Tables

Create a table

To create a table, you can use the Yiisoft\Db\Command\CommandInterface::createTable() method:

use Yiisoft\Db\Connection\ConnectionInterface;
use Yiisoft\Db\Schema\Column\ColumnBuilder;

/** @var ConnectionInterface $db */
$db->createCommand()->createTable(
    '{{%customer}}',
     [
        'id' => ColumnBuilder::primaryKey(),
        'name' => ColumnBuilder::string()->notNull(),
        'email' => ColumnBuilder::string()->notNull(),
        'status' => ColumnBuilder::integer()->notNull(),
        'created_at' => ColumnBuilder::datetime()->notNull(),
     ],
)->execute();

The library will automatically form and execute SQL suitable for the database used. For example, MSSQL connection will execute the following SQL:

CREATE TABLE [customer] (
    [id] int IDENTITY PRIMARY KEY,
    [name] nvarchar(255) NOT NULL,
    [email] nvarchar(255) NOT NULL,
    [status] int NOT NULL,
    [created_at] datetime NOT NULL
)

And the following SQL will be executed in MySQL/MariaDB:

CREATE TABLE `customer` (
    `id` int PRIMARY KEY AUTO_INCREMENT,
    `name` varchar(255) NOT NULL,
    `email` varchar(255) NOT NULL,
    `status` int NOT NULL,
    `created_at` datetime(0) NOT NULL
)

You can also define column types as strings. This is useful when you need to use a database-specific column type or when you need more flexibility in defining the column type:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createTable(
    '{{%customer}}',
     [
        'id' => 'pk',
        'name' => 'string(100) not null',
        'email' => 'string not null',
        'status' => 'integer not null',
        'created_at' => 'datetime not null',
     ],
)->execute();

Drop a table

To drop a table with schema declaration and all its data, you can use the Yiisoft\Db\Command\CommandInterface::dropTable() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropTable('{{%customer}}')->execute();

Warning: All existing data will be deleted.

Truncate a table

To clear just the data of a table without removing schema declaration, you can use the Yiisoft\Db\Command\CommandInterface::truncateTable() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->truncateTable('{{%customer}}')->execute();

Warning: All existing data will be deleted.

Columns

Add a new column

To add a new column to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::addColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;
use Yiisoft\Db\Mysql\Column;

/** @var ConnectionInterface $db */
$db->createCommand()->addColumn(
    '{{%customer}}',
    'profile_id',
     new Column('integer')
)->execute();

Alter a column

To change an existing column, you can use the Yiisoft\Db\Command\CommandInterface::alterColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;
use Yiisoft\Db\Mysql\Column;

/** @var ConnectionInterface $db */
$db->createCommand()->alterColumn(
    '{{%customer}}',
    'profile_id',
    new Column('integer')->notNull()
)->execute();

Rename a column

To rename an existing column, you can use the Yiisoft\Db\Command\CommandInterface::renameColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->renameColumn('{{%customer}}', 'profile_id', 'profile_id_new')->execute();

Drop a column

To drop an existing column, you can use the Yiisoft\Db\Command\CommandInterface::dropColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropColumn('{{%customer}}', 'profile_id')->execute();

Add default value to a column

To add a default value to an existing column, you can use the Yiisoft\Db\Command\CommandInterface::addDefaultValue() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addDefaultValue('{{%customer}}', 'df-customer-name', 'name', 'John Doe')->execute();

Drop default value from a column

To drop a default value from an existing column, you can use the Yiisoft\Db\Command\CommandInterface::dropDefaultValue() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropDefaultValue('{{%customer}}', 'df-customer-name')->execute();

Keys

Add a primary key

To add a primary key to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::addPrimaryKey() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addPrimaryKey('{{%customer}}', 'pk-customer-id', 'id')->execute();

Add a foreign key

To add a foreign key to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::addForeignKey() method:

use Yiisoft\Db\Connection\ConnectionInterface;
use Yiisoft\Db\Constant\ReferentialAction;

/** @var ConnectionInterface $db */
$db->createCommand()->addForeignKey(
    '{{%customer}}',
    'fk-customer-profile_id',
    'profile_id',
    '{{%profile}}',
    'id',
    ReferentialAction::CASCADE,
    ReferentialAction::CASCADE
)->execute();

Drop a primary key

To drop an existing primary key, you can use the Yiisoft\Db\Command\CommandInterface::dropPrimaryKey() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropPrimaryKey('{{%customer}}', 'pk-customer-id')->execute();

Drop a foreign key

To drop an existing foreign key, you can use the Yiisoft\Db\Command\CommandInterface::dropForeignKey() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropForeignKey('{{%customer}}', 'fk-customer-profile_id')->execute();

Indexes

Add an index

To add an index to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::createIndex() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createIndex('{{%customer}}', 'idx-customer-name', 'name')->execute();

Drop an index

To drop an existing index, you can use the Yiisoft\Db\Command\CommandInterface::dropIndex() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropIndex('{{%customer}}', 'idx-customer-name')->execute();

Add unique index

You can create a unique index by specifying the UNIQUE option in the $indexType parameter, it's supported by all DBMS:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createIndex('test', 'idx_test_name', 'id', 'UNIQUE')->execute();

Note: Unique indexes are indexes that help maintain data integrity by ensuring that no rows of data in a table have identical key values. When you create a unique index for an existing table with data, values in the columns or expressions that comprise the index key are checked for uniqueness.

Add clustered index

In MSSQL, you can create a clustered index by specifying the CLUSTERED option in the $indexType parameter:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createIndex('test', 'idx_test_name', 'id', 'CLUSTERED')->execute();

Note: A clustered index is an index which defines the physical order in which table records are stored in a database. Since there can be only one way in which records are physically stored in a database table, there can be only one clustered index per table. By default a clustered index is created on a primary key column.

Add non-clustered index

In MSSQL, you can create a non-clustered index by specifying the NONCLUSTERED option in the $indexType parameter:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createIndex('test', 'idx_test_name', 'id', 'NONCLUSTERED')->execute();

Note: A non-clustered index is also used to speed up search operations. Unlike a clustered index, a non-clustered index doesn’t physically define the order in which records are inserted into a table. In fact, a non-clustered index is stored in a separate location from the data table.

A non-clustered index is like a book index, which is located separately from the main contents of the book. Since non-clustered indexes are located in a separate location, there can be multiple non-clustered indexes per table.

Add fulltext index

In MySQL and MariaDB, you can create a fulltext index by specifying the FULLTEXT option in the $indexType parameter.

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->createIndex('test', 'idx_test_name', 'name', 'FULLTEXT')->execute();

Note: Full-text indexes are created on text-based columns (CHAR, VARCHAR, or TEXT columns) to speed up queries and DML operations on data contained within those columns.

A full-text index is defined as part of a CREATE TABLE statement or added to an existing table using ALTER TABLE or CREATE INDEX.

Add bitmap index

In Oracle, you can create a bitmap index by specifying the BITMAP option in the $indexType parameter:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */

$db->createCommand()->createIndex('test', 'idx_test_name', 'id', 'BITMAP')->execute();

Note: A bitmap index is a special kind of database index which uses bitmaps or bit array. In a bitmap index, Oracle stores a bitmap for each index key.

Each index key stores pointers to multiple rows. For example, if you create a bitmap index on the gender column of the members table.

Constraints

Add UNIQUE constraint

To add a unique constraint to an existing column, you can use the Yiisoft\Db\Command\CommandInterface::addUnique() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addUnique('{{%customer}}', 'uq-customer-name', 'name')->execute();

Drop UNIQUE constraint

To drop a unique constraint from an existing column, you can use the Yiisoft\Db\Command\CommandInterface::dropUnique() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropUnique('{{%customer}}', 'uq-customer-name')->execute();

Add CHECK constraint

To add a CHECK constraint to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::addCheck() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addCheck('{{%customer}}', 'ck-customer-status', 'status > 0')->execute();

Drop CHECK constraint

To drop an existing CHECK constraint, you can use the Yiisoft\Db\Command\CommandInterface::dropCheck() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropCheck('{{%customer}}', 'ck-customer-status')->execute();

Comments

Add comment to a column

To add a comment to an existing column, you can use the Yiisoft\Db\Command\CommandInterface::addCommentOnColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addCommentOnColumn('{{%customer}}', 'name', 'This is a customer name')->execute();

Add comment to a table

To add a comment to an existing table, you can use the Yiisoft\Db\Command\CommandInterface::addCommentOnTable() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->addCommentOnTable('{{%customer}}', 'This is a customer table')->execute();

Drop comment from a column

To drop a comment from an existing column, you can use the Yiisoft\Db\Command\CommandInterface::dropCommentFromColumn() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropCommentFromColumn('{{%customer}}', 'name')->execute();

Drop comment from a table

To drop a comment from an existing table, you can use the Yiisoft\Db\Command\CommandInterface::dropCommentFromTable() method:

use Yiisoft\Db\Connection\ConnectionInterface;

/** @var ConnectionInterface $db */
$db->createCommand()->dropCommentFromTable('{{%customer}}')->execute();