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If a table column has is UNIQUE and has NOT NULL, is it
equivalent to a PRIMARY KEY column?
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Answer / murugananthan
NO, UNIQUE +NOT NULL != PRIMARY KEY
it cant refer someother table column
| Is This Answer Correct ? | 12 Yes | 2 No |
Answer / yuva
No. It can be at table level, but this will get failed
while referencing in another table.
| Is This Answer Correct ? | 13 Yes | 5 No |
Answer / kuldeep singh
Primary Key=Unique+Not Null+Sorting+Cluster Index
So
UNIQUE +NOT NULL != PRIMARY KEY
it cant refer someother table column
| Is This Answer Correct ? | 2 Yes | 0 No |
No. Generally Primary Key contains Unique + NotNull values.
If we are not defined a column as Primay Key and we defined
as Unique + NotNull, then, the behavior of that particular
column in that particular table looks like primary key. but
this cannot be referenced in any other table as we have not
defined as primary key..So, Primary Key column is different
from the column which have Unique + Not Null qualities.
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / ananta pilaka
Primary key is only one and it is clustered index.
Unique key cannot be referred as foreign key contraint of
another table.
| Is This Answer Correct ? | 2 Yes | 2 No |
no. bcoz we can insert null values in the column which
contains the combination of constraints as
UNIQUE+ NOT NULL
but in case of primary key we can't use null values in that
primary key column
| Is This Answer Correct ? | 2 Yes | 8 No |
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