Join不返回某些行

Question

我需要访问字段IsAvailable才能在条件语句中使用它。此字段存储在Table5中

下面的查询返回48行：

select *
from Table1 c
join Table2 cm      on c.candidateId = cm.candidateId

我对其进行了更改并添加了一些连接，因此现在可以访问Table5中的字段IsAvailable，但现在它返回23行，而我需要获取48行

select *
from Table1 c
join Table2 cm      on c.candidateId = cm.candidateId
join Table3 lpg     on c.positionId = lpg.positionId
join Table4 lpt     on lpg.linkPositionGradeId = lpt.linkPositionGradeId
join Table5 s       on lpt.linkPositionTeamId = s.linkPositionTeamId

如何获取48行？

Answer 1

使用left join

select *
from Table1 c
join Table2 cm      on c.candidateId = cm.candidateId
left join Table3 lpg     on c.positionId = lpg.positionId
left join Table4 lpt     on lpg.linkPositionGradeId = lpt.linkPositionGradeId
left join Table5 s       on lpt.linkPositionTeamId = s.linkPositionTeamId