please explain how does this join work

[#1]

Hi Guys,

can someone please explain how does the below join work in the bottom query. Its from thisl tutorial. I don't get the bit after "concat". thanks

ON o.swid = concat('{', u.swid ,'}');

CREATE TABLE webloganalytics as
SELECT to_date(o.ts) logdate, o.url, o.ip, o.city, upper(o.state) state,
o.country, p.category, CAST(datediff(from_unixtime(unix_timestamp()), from_unixtime(unix_timestamp(u.birth_dt,'dd-MMM-yy')))/365 AS INT) age, u.gender_cd
FROM omniture o
INNER JOIN products p
ON o.url = p.url
LEFT OUTER JOIN users u 
ON o.swid = concat('{', u.swid ,'}');

[#2 · Accepted solution]

Hi @Harjinder Brar

concat('{', u.swid ,'}') will concatenate bracs with the value from u.swid. For Example if the value of u.swid is TEST then it will be converted to {TEST} which will be used to join with o.swid column. Hope it Helps!!