如何在MySQL中为两个单独的表创建自动增量ID字段？

Question

I have two tables (A and B) and I want each record in these tables to have an unique ID (id_C). How do I do that?

TABLE_A:

id_A | id_C
 1      1
 2      3

TABLE_B:

id_B | id_C
 1      2
 2      4

PS. I was thinking about something like this:

create table c(
    id_c int not null auto_increment,
    PRIMARY KEY(id_c)
);

create table a(
    id_a int not null auto_increment,
    a_c  int not null,
    PRIMARY KEY(id_a),
    FOREIGN KEY (a_c) REFERENCES c(id_c)
);

create table b(
    id_b int not null auto_increment,
    b_c  int not null,
    PRIMARY KEY(id_b),
    FOREIGN KEY (b_c) REFERENCES c(id_c)
);

Answer 1

Create a table which contains your IDs and make it an auto-incrementing primary key. Use this table to generate unique ids and reference them with foreign key constraints from the other tables. I think this is what you suggested in your question.

Another alternative is to use a GUID .