public function onDuplicateKeyUpdate($key, $value = null)
    {
        if( func_num_args() == 2 ) {
            $this->onDuplicateKeyUpdate[$key] = $value;
        } else if( $key instanceof Expression ) {
            $this->onDuplicateKeyUpdate[] = $key;
        } else if( is_array($key) ) {
            $this->onDuplicateKeyUpdate = $key;
        }
        return $this;
    }
public function onDuplicateKeyUpdate($key, $value = null)
    {
        if( func_num_args() == 2 ) {
            $this->onDuplicateKeyUpdate[$key] = $value;
        } else if( $key instanceof Expression ) {
            $this->onDuplicateKeyUpdate[] = $key;
        } else if( is_array($key) ) {
            $this->onDuplicateKeyUpdate = $key;
        }
        return $this;
    }
public function onDuplicateKeyUpdate ( $ key , $ value = null ) { if ( func_num_args ( ) == 2 ) { $ this -> onDuplicateKeyUpdate [ $ key ] = $ value ; } else if ( $ key instanceof Expression ) { $ this -> onDuplicateKeyUpdate [ ] = $ key ; } else if ( is_array ( $ key ) ) { $ this -> onDuplicateKeyUpdate = $ key ; } return $ this ; }
Set on duplicate key update clause

@param string|Expression $key
@param mixed $value
@return $this
Set on duplicate key update clause