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What is difference between UNIQUE and PRIMARY KEY constraints?
What is difference between UNIQUE and PRIMARY KEY constraints?
✍: Guest
An UNIQUE key can have NULL whereas PRIMARY key is always not NOT NULL. Both bears unique values.
2011-12-22, 3070👍, 0💬
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What are various joins used while writing SUBQUERIES?
What are various joins used while writing SUBQUERIES? =, , IN, NOT IN, IN ANY, IN ALL, EXISTS, NOT EXISTS. 2011-12-23, 3302👍, 0💬
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