wahts is mean by primary key and unique key?
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Answer / swapna
Primery Key:- A column or set of columns that uniquely
identify all the rows in a table. Primary keys do not allow
null values. No two rows can have the same primary key
value; therefore, a primary key value always uniquely
identifies a single row.
Unique Key:- Unique Keys are used to uniquely identify each
row in an Oracle table. There can be one and only one row
for each unique key value. no value repeate in the other
rows of the same table.
| Is This Answer Correct ? | 21 Yes | 7 No |
Answer / seshu
HI ALL
PRIMARY KEY :- UNIQUE+NOT NULL
UNIQUE kEY :- UNIQUE +NULL
| Is This Answer Correct ? | 13 Yes | 0 No |
Answer / m.karthikeyan
hi dear friends....
unique key is also act as a primary key but it accept the
null values that is the difference b/w them...
| Is This Answer Correct ? | 14 Yes | 3 No |
Answer / anjani kumar jha
always remember
in 1 table there must be only on primary key,but may have
more than on unique key
| Is This Answer Correct ? | 12 Yes | 4 No |
Answer / bhausaheb.chate
Primary Key:- Primary Key is an attribute or a set of
attributes in a table which uniquely identifies a record
(row) in a table and no two records (rows) in the table can
have the same values for all the columns comprising the
primary key.
Unique Key:- A unique key is a key which stores unique
values (no duplicates) for that particular column.
Difference between Primary Key & Unique Key:-
1. A Unique key can store a null value and primary key
cannot store any null value.
2. A primary key can be references to another table as a
Foreign Key.
| Is This Answer Correct ? | 7 Yes | 2 No |
Answer / murugan
A Column or set of Columns that uniquely identify all the
rows in a table......
| Is This Answer Correct ? | 4 Yes | 6 No |
Answer / bhausaheb.chate
A Column or set of Columns that uniquely identify all the
rows in a table .......
| Is This Answer Correct ? | 3 Yes | 6 No |
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