framework/db/ActiveQuery.php
public function alias($alias)
    {
        if (empty($this->from) || count($this->from) < 2) {
            list($tableName) = $this->getTableNameAndAlias();
            $this->from = [$alias => $tableName];
        } else {
            $tableName = $this->getPrimaryTableName();

            foreach ($this->from as $key => $table) {
                if ($table === $tableName) {
                    unset($this->from[$key]);
                    $this->from[$alias] = $tableName;
                }
            }
        }

        return $this;
    }
public function alias($alias)
    {
        if (empty($this->from) || count($this->from) < 2) {
            list($tableName) = $this->getTableNameAndAlias();
            $this->from = [$alias => $tableName];
        } else {
            $tableName = $this->getPrimaryTableName();

            foreach ($this->from as $key => $table) {
                if ($table === $tableName) {
                    unset($this->from[$key]);
                    $this->from[$alias] = $tableName;
                }
            }
        }

        return $this;
    }
public function alias ( $ alias ) { if ( empty ( $ this -> from ) || count ( $ this -> from ) < 2 ) { list ( $ tableName ) = $ this -> getTableNameAndAlias ( ) ; $ this -> from = [ $ alias => $ tableName ] ; } else { $ tableName = $ this -> getPrimaryTableName ( ) ; foreach ( $ this -> from as $ key => $ table ) { if ( $ table === $ tableName ) { unset ( $ this -> from [ $ key ] ) ; $ this -> from [ $ alias ] = $ tableName ; } } } return $ this ; }
Define an alias for the table defined in [[modelClass]].

This method will adjust [[from]] so that an already defined alias will be overwritten.
If none was defined, [[from]] will be populated with the given alias.

@param string $alias the table alias.
@return $this the query object itself
@since 2.0.7
Define an alias for the table defined in [[ modelClass ]] .