mysql - Did my union work? -

we in process of making in school version of facebook aka tigerbook now. have created following 3 data tables.

users:

user    name 1       hallie   2       dylan 3       sarina 4       dominic 

friends:

user    friend 1       2 1       3 1       4 2       1 3       1 4       1 2       4 4       2 3       2 2       3 

posts:

user    postid  post 1       101     tigerbook! 2       102     pregnant. 1       103     peeps 4       104     giant buzz lightyears rock. 3       105     die tucker die 1       106     murhur de derpity derp 2       107     banana spaghetti squid 4       108     chicken 

we used syntax of:

select user users union select user friends union select user posts; 

and came this:

user 1 2 1 4 

all wondering if join worked or if should try else. we've tried left joins , full joins, nothing has worked well.

and on side note: when connect php code web page automatically generate users when create login or have create users before make login?

well that's not join... it's union removed duplicates of user across 3 tables.. answer question, union worked. if want join users posts, need like

select a.user, a.name, b.postid, b.post users join posts b on b.user = a.user 

this produces

| user |    name | postid |                        post | --------------------------------------------------------- |    1 |  hallie |    101 |          tigerbook! | |    2 |   dylan |    102 |              pregnant. | |    1 |  hallie |    103 |                peeps | |    4 | dominic |    104 | giant buzz lightyears rock. | |    3 |  sarina |    105 |              die tucker die | |    1 |  hallie |    106 |      murhur de derpity derp | |    2 |   dylan |    107 |      banana spaghetti squid | |    4 | dominic |    108 |                     chicken |

see demo