尝试在 SQL Server 2008R2 中创建新的外键关系时出错

Question

while trying to create a new foreign key constraint in SQL Server using the following syntax:

alter table fkTable add constraint FK_fkTable_pkTable 
foreign key (pkTable_Id) references pkTable(pkTable_Id)

I get the following error:

Msg 50000, Level 16, State 0, Line 218 Could not create constraint. See previous errors.

this was literally the only message, there were no previous errors.

Answer 1

The problem was that my tables were defined as:

create table pkTable (
    pkTable_Id smallint not null constraint PK_pkTable primary key identity(1,1),
    --other columns...
)

create table fkTable (
    fkTable_Id uniqueidentifier not null constraint primary key,
    pkTable_Id int not null,
    --other columns...
)

Where the pkTable_Id column is defined as a smallint on the pkTable, and int on the fkTable. Might seem pretty obvious but the error was not at all helpful!