safeDown() public method This method contains the logic to be executed when removing this migration. This method differs from down() in that the DB logic implemented here will be enclosed within a DB transaction. Child classes may implement this method instead of down() if the DB logic needs to be within a transaction. public boolean safeDown ( )return boolean Return a false value to indicate the migration fails and should not proceed further. All other return values mean the migration s

renameColumn() public method Builds and executes a SQL statement for renaming a column. public void renameColumn ( $table, $name, $newName )$table string The table whose column is to be renamed. The name will be properly quoted by the method. $name string The old name of the column. The name will be properly quoted by the method. $newName string The new name of the column. The name will be properly quoted by the method.

init() public method Initializes the migration. This method will set $db to be the 'db' application component, if it is null. public void init ( )

insert() public method Creates and executes an INSERT SQL statement. The method will properly escape the column names, and bind the values to be inserted. public void insert ( $table, $columns )$table string The table that new rows will be inserted into. $columns array The column data (name => value) to be inserted into the table.

execute() public method Executes a SQL statement. This method executes the specified SQL statement using $db. public void execute ( $sql, $params = [] )$sql string The SQL statement to be executed $params array Input parameters (name => value) for the SQL execution. See yii\db\Command::execute() for more details.

getDb() protected method (available since version 2.0.6) protected void getDb ( )

dropPrimaryKey() public method Builds and executes a SQL statement for dropping a primary key. public void dropPrimaryKey ( $name, $table )$name string The name of the primary key constraint to be removed. $table string The table that the primary key constraint will be removed from.

dropForeignKey() public method Builds a SQL statement for dropping a foreign key constraint. public void dropForeignKey ( $name, $table )$name string The name of the foreign key constraint to be dropped. The name will be properly quoted by the method. $table string The table whose foreign is to be dropped. The name will be properly quoted by the method.

dropIndex() public method Builds and executes a SQL statement for dropping an index. public void dropIndex ( $name, $table )$name string The name of the index to be dropped. The name will be properly quoted by the method. $table string The table whose index is to be dropped. The name will be properly quoted by the method.

dropTable() public method Builds and executes a SQL statement for dropping a DB table. public void dropTable ( $table )$table string The table to be dropped. The name will be properly quoted by the method.