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POReferencing foreign keys in the same column
 

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    <p>I'm designing a bd-scheme for mysql. My db stores 3 kinds of points: a, b or c and a path is composed by n pair of points:</p> <p>Route = [ (a1 or b1 or c1 ; a2 or b2 or c2), (a2 or b2 or c2 ; a3 or b3 or c3), ...]</p> <pre><code>create table a_points ( point_id serial not null, owner_id bigint unsigned not null, name varchar(20) not null, primary key (point_id), foreign key (owner_id) references othertable (other_id) ) engine = InnoDB; create table b_points ( point_id serial not null, owner_id bigint unsigned not null, name varchar(20) not null, fields varchar(20) not null, primary key (point_id), foreign key (owner_id) references othertable (owner_id) ) engine = InnoDB; create table c_points ( point_id serial not null, name varchar(20) not null, cfields varchar(20) not null, primary key (point_id) ) engine = InnoDB; create table paths ( path_id serial not null, name varchar(20) not null, primary key (path_id) ) engine = InnoDB; create table point_pairs ( pair_id serial not null, path_id bigint unsigned not null, point_from bigint unsigned not null, point_to bigint unsigned not null, table_from varchar(9) not null, table_to varchar(9) not null, primary key (pair_id), foreign key (path_id) references paths (path_id) ) engine = InnoDB; </code></pre> <p>(*) a pair of point is (m, n) or from m to n</p> <p>So I'm storing pair of points together with their path's id. My problem is that I had to create two columns identifying the tables' name of m and n. table_from for m and table_to for n. Thus I'd have to use these two columns in my code to know what kind of points are saved in a route (path and point_pairs table). My question: Does MySql provide something for referencing n foreign keys in the same column? I already thought about joining a, b and c point tables but I'd have to add a type column to this new table and my php classes would become useless.</p> <p>Thanks in advance!</p>
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