framework/db/Command.php
public function addColumn($table, $column, $type)
    {
        $sql = $this->db->getQueryBuilder()->addColumn($table, $column, $type);

        return $this->setSql($sql)->requireTableSchemaRefresh($table);
    }
public function addColumn($table, $column, $type)
    {
        $sql = $this->db->getQueryBuilder()->addColumn($table, $column, $type);

        return $this->setSql($sql)->requireTableSchemaRefresh($table);
    }
Creates a SQL command for adding a new DB column.
@param string $table the table that the new column will be added to. The table name will be properly quoted by the method.
@param string $column the name of the new column. The name will be properly quoted by the method.
@param string $type the column type. [[\yii\db\QueryBuilder::getColumnType()]] will be called
to convert the give column type to the physical one. For example, `string` will be converted
as `varchar(255)`, and `string not null` becomes `varchar(255) not null`.
@return $this the command object itself