计算mysql中两个表之间的公共行

Question

so here's my question...

Hi have two tables in mysql, called go_H and go_J, both looking like this:

go_H

+---------------+------------+
| gene          | GoCode     |
+---------------+------------+
| DNAJC25-GNG10 | GO:0004871 |
| DNAJC25-GNG10 | GO:0005834 |
| DNAJC25-GNG10 | GO:0007186 |
| LOC100509620  | GO:0005215 |
| LOC100509620  | GO:0006810 |
| LOC100509620  | GO:0016021 |
| PPIAL4E       | GO:0000413 |
| PPIAL4E       | GO:0003755 |
| PPIAL4E       | GO:0005737 |
| PPIAL4E       | GO:0006457 |
| LOC105371242  | GO:0000413 |
+----------------------------+

go_J

+------------+
| GoCode     |
+------------+
| GO:0007254 |
| GO:0007256 |
| GO:0007257 |
| GO:0042655 |
| GO:0043506 |
| GO:0043507 |
| GO:0043508 |
| GO:0046328 |
| GO:0046329 |
| GO:0046330 |
+------------+

Basically what I want to achieve is to see what GoCode values from go_J appear in GoCode from Go_H, and count them, so as I get a total number o GO ids that are present in both tables.

I have come to select go_H.GoCode and go_J.GoCode, but I don't know how to compare them to find common rows and then count them...

Any help?

Answer 1

Hope this helps.

select count(*) from go_J j join  go_H h on h.GoCode=j.GoCode;