如果存在PHP MYSQL UPDATE或不存在INSERT？?mysql

我不知道这是否真的正确。我有一个班级，如果这些字段当前存在，我想在其中更新数据库，如果不存在则要插入。复杂的是，我正在联接3个表（set_colors，school_art，baseimage）

任何帮助都将非常棒。

这是我所拥有的：

public function set_layer_colors($value) { global $db;

$result_array = mysql_query("
IF EXISTS(SELECT * FROM set_colors WHERE school_art_id = '{$value}')

  UPDATE set_colors (school_art_id, baseimage_id, sub_folder, layer)
    SELECT school_art.id, baseimage.id, baseimage.sub_folder, baseimage.layer
    FROM school_art 
    JOIN baseimage ON baseimage.base_folder = school_art.series_code 
    WHERE baseimage.image_type = 'B' ORDER BY school_art.id 

ELSE

 INSERT INTO set_colors (school_art_id, baseimage_id, sub_folder, layer)
    SELECT school_art.id, baseimage.id, baseimage.sub_folder, baseimage.layer
    FROM school_art 
    JOIN baseimage ON baseimage.base_folder = school_art.series_code 
    WHERE baseimage.image_type = 'B' ORDER BY school_art.id 
    ");

return $result_array;

}