请教这个SQL语句是什么意思

Question

AND a.shipment_gid = e.shipment_gid(+)
and a.source_location_gid = e.event_location_gid(+)
AND a.shipment_gid = F.shipment_gid(+)
and a.source_location_gid = F.event_location_gid(+)
AND a.shipment_gid = g.shipment_gid(+)后面的（+）是什么意思

Answer 1

(+)
 好像是left不就是right join,是以前老的写法

Answer 2

以a表为左表和其他表做leift join

Answer 3

举个例子
a表                  b表id name            id   score 
1   jim             1     90
2   xiaoming用带加号连接，查出来的是
id name       score
1   jim         90
2   xiaoming

Answer 4

举个例子
a表 
id name
1 jim 
2 xiaoming
b表
 id score  
  1   90用带加号连接，查出来的是
id name    score
1  jim      90
2 xiaoming

Answer 5

--左连接  相反则右连接AND a.shipment_gid = e.shipment_gid(+)
and a.source_location_gid = e.event_location_gid(+)
AND a.shipment_gid = F.shipment_gid(+)
and a.source_location_gid = F.event_location_gid(+)
AND a.shipment_gid = g.shipment_gid(+)--等同于
left a join e on a.shipment_gid = e.shipment_gid 
and a.source_location_gid = e.event_location_gid
left a join f on a.shipment_gid = F.shipment_gid 
and a.source_location_gid = F.event_location_gid
left a join g  on a.shipment_gid = g.shipment_gid