能否建立这样的约束？

[happywwh]

table1(a,b,c,d)
能否约束同一记录中列b和列c中只出现一个值，即：要么b有值，c为空，要么b为空，c有值。

[gmlxf]

create table #table1(
a int,
b int,
c int,
d int,
check((b is not null and c is null) or (b is null and c is not null)))

insert #table1 values(1,2,null,4) -- ok
insert #table1 values(1,null,3,4) -- ok
insert #table1 values(1,null,null,4) -- error
insert #table1 values(1,2,3,4) -- error

drop table #table1

[gmlxf]

alter table table1 with nocheck add constraint c_check check((b is null and c is not null) or (b is not null and c is null))

[pengdali]

create table table1(a int,b int check( (b is not null and c is null) or (b is null and c is not null) ) )

[txlicenhe]

alter table table1 add constraint ck_1 check((b is null and c is not null) or (b is not null and c is null))

[sai1691]

create table table1(a int,b int check( (b is not null and c is null) or (b is null and c is not null) ) ，d int)

[eddiezhuo]

create table t(a int,b int check( not exists (a is null and b is null) )