What is meant by Query Processing?

Query Processing:   When we sent an sql Query from Sql Command Prompt to Data Base,then Database Engine we perform the following steps.

1.)Query Tokenization: In this phase it will take the provided Sql Query as input and divide into number of tokens,and generate stream of tokens as output.

2.)Query Parsing:T his phase will take stream of token as input and trying to construct a tree,If the tree is constructed successfully means there is no syntactical errors in provided SQL Query.

3.)Query Optimization:This phase will take the constructed tree as i/p and perform n.o optimization mechanisms in order to decrease the execution time and memory utilization.

4.)Query Execution:  This phase will take Query Optimization as i/p and execute by using n.o of interceptors internally.

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