mysql - Sql: Setting distinct for one value of one column -

mysql - Sql: Setting distinct for one value of one column -

is possible set if seek created table 2 values match , 1 value specific value say, 1, won't allow you?

i want have table this:

table1_id: | table1_name: 1 | edgar 2 | rudy table2_id: | table2_table1_id |table2_active(bit): 1 | 1 | 1 (this okay) 2 | 1 | 0 (this okay) 3 | 1 | 1 (this not okay) // shouldn't work 4 | 1 | 0 (this still okay) 5 | 2 | 1 (this okay) 6 | 2 | 0 (this okay) 7 | 2 | 1 (this not okay) // shouldn't work 8 | 2 | 0 (this still okay)

i want able have many (x,0s) want able have 1 (x,1) how accomplished?

edit: possible solution:

create trigger active_check before insert on table2` if exists (select table2_id table_2 table2_table1_id = new.table2_table1_id active = 1) begin rollback transaction; homecoming end;

would utilize of new.table2_table1_id work here though it's in own statement? if not how around that?

mysql sql unique distinct