Once the tokens are generated, they are verified for their correctness by the parser. It then scans the query and divides it into individual tokens.
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When a query is submitted to the database, it is received by the query compiler. The above diagram depicts how a query is processed in the database to show the result. A query processor in DBMS performs this task. It is the step-by-step process of breaking the high-level language into a low-level language in which the machine can understand and perform the requested action for the user. All these processes are together known as query processing in DBMS. It then selects the best execution path and executes the query and gets the data from internal memory.
#QUERY PROCESSING IN DBMS CODE#
It verifies the code written by the user and then converts them into low-level languages. Hence what DBMS does is it ask its users to write queries in SQL. But it will be difficult for any user to directly write relational algebra kinds of queries. Usually, any query written in SQL is converted into low-level language using relational algebra which the system can understand. There has to be some low-level language that these systems can understand. But the underlying systems in the DBMS will not understand SQL. This SQL is a high-level language created to build a bridge between users and DBMS for their communication. Hence the users are asked to query the database in its language – SQL. But DBMS has its own language (SQL) which it understands.
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The user can request the data in a language that he understands. it should be accessed easily and quickly.īut a database is a system and the users are either another system or application or a person. Accessing and manipulating the data should be done efficiently i.e. Query Processing in DBMS – The main goal of creating a database is to store the related data at one place, access and manipulate them as and when it is required by the user.
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