从链接到许多表的另一个表的主键中获取外键字段

Question

My database is designed in SQL Server & I want get output in asp.net, LINQ, C#

I have 2 tables linked to 1 table (1:1)

My question is can I get a primary key linked to which table?

For example:

• tbl_Document (ID, Date, ...)
• tbl_Factor (ID, DocID, ...)
• tbl_Finance (ID, DocID, ...)

What is the best way to know ID in tbl_Document linked to which table?

I can add record in tbl_Document as 'whichTable' and write the name of table in every column, and every time I want to search set "if" and check 'WhichTable'.

Is there a better way to do that?

Thanks, and sorry for my bad English :)

Answer 1

By default, you can get only all tables that have foreign key constraints to the parent table:

select  object_name(f.referenced_object_id) pk_table, c1.name pk_column_name,
  object_name(f.parent_object_id) fk_table, c2.name fk_column_name
from
sys.foreign_keys f
join sys.columns c1 on c1.object_id = f.referenced_object_id
join sys.columns c2 on c2.object_id = f.parent_object_id 
join sys.foreign_key_columns k 
  on (k.constraint_object_id = f.object_id 
    and c2.column_id = k.parent_column_id
    and c1.column_id = k.referenced_column_id )
where object_name(f.referenced_object_id) ='tbl_Document'

There is no such additional information regarding every particular row in parent table. It would be a duplicate information (since you can figure out it by searching in every child table). Thus, as you mentioned you can store child table name in the additional column and then as an option, construct sql dynamically to query child row.