sql - MYSQL | select inverse value between 2 tables -
i select records table have different values one.
table 1.
+--------+-------+ | userid | tagid | +--------+-------+ | 1 | 2 | | 1 | 3 | | 1 | 4 | +--------+-------+
table 2.
+---------+-------+ | chaname | tagid | +---------+-------+ | hello | 1 | | how | 2 | | | 3 | | | 4 | | today | 5 | | guys | 6 | | ? | 7 | +---------+-------+
and suppose be
+--------+-------+---------+ | userid | tagid | chaname | +--------+-------+---------+ | 1 | 1 | hello | | 1 | 5 | today | | 1 | 6 | guys | | 1 | 7 | ? | +--------+-------+---------+
it looks simple can't find way solve it.
thank of answers <3
ps. btw i've tried use ' not in ' got error
unrecognized keyword. (near "not in" @ position 92)
to output, need use outer join
. left join
give records left table table2
, matching records right table table1
. means null
records in table1
doesn't exist in table2
. can use property in where
clause expected records.
also cannot decide on userid
on records in table2
. if want hardcode them 1
, use select 1 userid, ...
in select
clause.
select t2.tagid,t2.chaname table2 t2 left join table1 t1 on t1.tagid=t2.tagid t1.tagid null
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