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what is primary key,unique key, foreign key? can u teach me
in simple language?
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Answer Posted / mohamed ibrahim
Primary Key :- Is a unique identify a table data,it is avoid null and duplicate value.In a table we can assign single primary key.
Unique Key :- Is same as primary key but it allow single null value and avoid duplicate value.In a table we can assign more than one no of unique key.
Foreign Key :- Is a connect two table from a single column name.
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