Combining Columns from 2 different tables

Hello! I'm trying to combine several columns from 2 different tables, and I'm having trouble...
When I run this report, it does what I want it to, and pulls the information that I need from the primary table. It gives me the right query to select date/time and everything.
{$translate_lookup_exclusive|operator_his}
SELECT operator_his.opr_activity_date, operator_his.opr_activity_time, operator_his.login_id, operator_his.employee, operator_his.record_desc, operator_his.xact_type, operator_his.table_id, operator_his.value, operator_his.facility
FROM operator_his
WHERE operator_his.table_id = 154 AND
{$time_range_exclusive|report.DateAndTime|report.Operator|report.Host|report.UTC|opr_activity|host_activity|utc_activity} AND
xact_type IN (9) AND
(facility IN (33,31,20,17,39,19,38,37,35,15,-1,4,10,34,21,8,30,23,1,25,2,12,24,36,32,27,9,22,28,26) OR facility IS NULL)
What I'm trying to add to this is the final report is the field badge_history.employee from the table badge_history. I tried adding it to the SQL that works, but it continues to give me an error every time. I think I'm just putting it together wrong or something...
Any suggestions would be GREATLY appreciated!