加入不返回某些行[重复]

Question

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

下面的查询返回 48 行：

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

我更改了它并添加了一些连接，所以现在我可以访问 Table5 中的字段 IsAvailable，但现在它返回 23 行，我需要得到 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

如何获得 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