ques 2.
consider primary key of parent table acts foreign key for child table which is a composite key their are 16 diff combinations How ?
In oracle
2006-12-20 03:02:58 · 3 answers · asked by Anonymous in Computers & Internet ➔ Programming & Design
Composite key is a key, formed by the elements of more than one coloumns. Individually the elements of those coloumns may not be unique. But the when u consider the whole combination along a row, they r unique.
Your question 2 is not very clear. For one possible interpretation read the following statements carefully.
1>There's a composite primary key in the parent table.
2> There r 16 unique combinations for that primary key.
3>That primary key acts as a foreign key to the child table.
O.K.?
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2006-12-20 06:27:31 · answer #1 · answered by binaryFusion 5 · 0⤊ 1⤋
A composite key is nothing but key combinations that can uniquely identify a row.
When to go for it?
When a single column cannot identify a row then u go for composite primary key.
2006-12-20 12:40:16 · answer #2 · answered by Sudha P 2 · 0⤊ 0⤋
A composite key is a table key that consists of more than one column.
I don't really understand the second question. There are potentially millions of combinations depending on the number of columns in a composite key.
2006-12-20 11:22:54 · answer #3 · answered by Elizabeth Howard 6 · 1⤊ 0⤋