what is Constraint? How many types of constraints in SQL ?
Answer Posted / nambi rajan
A constraint is a property assigned to a column or the set
of columns in a table that prevents certain types of
inconsistent data values from being placed in the columns.
There are 4 Types of Constraints.
• Entity Integrity - Primary and Unique
• Domain Integrity - Default, Check and Not Null
• Referential integrity – Foreign Key
• User-Defined Integrity - enforces some specific
business rules that do not fall into entity, domain, or
referential integrity categories
| Is This Answer Correct ? | 13 Yes | 7 No |
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