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Difference between UNION ALL and UNION. UNION statement eliminates duplicate rows whereas UNION ALL statement includes duplicate rows. UNION statement can be used to combine any number of queries whereas UNION ALL statement can be used to combine a maximum of two queries. UNION statement cannot be used with aggregate functions whereas UNION ALL statement can be used with aggregate functions
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What are the different types of Locks?Shared Lock: Shared locks are used for operations that read data, such as a SELECT statement. During Shared locks used, concurrent transactions can read a resource, but cannot modify the data.......
