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 Question: 689 Page Views: 

How are Primary Key and Foreign key inter-related?



Posted By: Avi Date: 1 October 2010 11:07:06 AM
 Answer:

Primary Key is a column or combination of columns to have unique records in the table. There can only be one Primary Key in a table. A foreign key is a column or combination of columns to enforce a relation between the two tables. The Primary Key of table becomes the forign key in the second table. Such as if take an example there are two tables "Stud" and "result". Table 1 i.e. "stud" is having roll_number , name,class, as its fields. In this table the roll_number field is a Primary Key. Hence no two rows will have the same roll_number. Now in the second table i.e. "result" the fields are roll_number,sub1,sub2,sub3 and total. Here this table is related to "stud" table by making "roll_number " the foreign key.


Posted By: avibtech

Date: 1 October 2010 11:07:06 AM
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