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What is difference b/w composit key n primary key and
forigion key?
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Answer Posted / saraswathi muthuraman
Compost key :
More than one column will be used to create compst key
SQL> create table ts_250 (a number,b number,c number,
primary key(a,c));
Table created.
here column A and column C is used to create compst key.
U can't insert null value in both columns.
Only unique combination of column A and column B value can
be inserted.
Primary key :
Key will be created on a single column in table.
SQL> create table ts_251 (a number,b number,c number,
primary key(a));
Table created.
null value cann't be inserted into column a.
oracle will create a index
only unique value can be inserted into column a.
only one primary key can be created on a table
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