Firebird'更新或插入'带有值的字段引用？

Question

我想在Firebird 2.5表中更新或插入一行,但是如果它们为null,我希望忽略我插入的值.

我希望这样的事情会这样做:

update or insert into TargetTable
  ( FieldA, FieldB )
values
  ( :fielda, coalesce(:fieldb, FieldB ))

但是,Firebird不允许在"值"列表中引用FieldB.

它确实允许这种更新语法:

update TargetTable
  set FieldB = coalesce( :fieldb, FieldB )
where
  FieldA = :fielda

但这需要我单独处理插入物.

有没有办法在字段值上同时获得更新/插入和合并？

Answer 1

看看这里:http://tracker.firebirdsql.org/browse/CORE-3456

您可以查看MERGE语句:http://www.firebirdsql.org/refdocs/langrefupd21-merge.html

merge into TargetTable e
using (select :fielda FieldA, :fieldb FieldB from RDB$DATABASE ) n
on e.FieldA = n.FieldA
when matched then
  update set e.FieldB = coalesce( n.FieldB, e.FieldB )
when not matched then
  insert (FieldA, FieldB) values ( n.FieldA, n.FieldB )