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Difference Between MySQL PRIMARY KEY and UNIQUE Constraint
The following table will provide us the differences between PRIMARY KEY and UNIQUE constraint −
| PRIMARY KEY |
UNIQUE Constraint |
|---|---|
| 1. Only one Primary key can be created on a table. |
1. More than one UNIQUE Constraints can be added to a table. |
| 2. Primary key creates clustered index by default. |
2. UNIQUE Constraint creates a non-clustered index by default. |
| 3. We cannot insert null values in the column which is defined as PRIMARY KEY. |
3. We can insert null values in the column having a UNIQUE constraint. |
Updated on: 2020-06-19T13:31:07+05:30
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