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GeekInterview.com > Interview Questions > Database > SQL
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Question: What is difference between Co-related sub query and nested sub query?
Answer: Co-related sub query is one in which inner query is evaluated only once and from that result outer query is evaluated.
Nested query is one in which Inner query is evaluated for multiple times for gatting one row of that outer query.
ex. Query used with IN() clause is Co-related query.
Query used with = operator is Nested query |
| May 05, 2007 08:26:32 |
#3 |
| Tushar |
Member Since: Visitor Total Comments: N/A |
RE: What is difference between Co-related sub query an...
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| When we need distinct with join we use corelated sub query (where exists clause) which works faster than nested sub query |
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