DB Locks in SQL

1. What is a database lock in the context of SQL? When two sessions or users of database try to update or delete the same data in a table, then there will be a concurrent update problem. In order to avoid this problem, database locks the data for the first …

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Keys in SQL

What is a key? Why do we need them in SQL? A database is composed of tables. Each table has lots of records / rows of data. Each row will contain unique information about any object. That means each table in the database is designed to represent any real world …

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Optimization in SQL

1. What is Optimization? Optimization is part of RDBMS. It analyzes the query and tells the parser which path is the best path to execute the query. This is very much essential because when best path is selected to execute the query, it saves lots of time and resource. Consider …

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Oracle in SQL

1) What is oracle database? Oracle Database is developed on the basis of relational database management system (RDBMS) It can store and retrieve the large amounts of data. It has both physical and logical structures which work independently of each other. 2) What is schema? A schema is a user …

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