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Explain Relational model and their use in DBMS?
Relational Model - The relational model was first introduced through E.F. Codd of the IBM Research in the year of 1970. The model uses the concept of a mathematical relation (like a table of values) as its primary building block, and has its theoretical basis in set theory and first-order predicate logic. The relational model presents the database as a collection of relations.
If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words,
Define shadow paging. An alternative to log-based crash recovery method is shadow paging. This technique requires fewer disk accesses than do the log-based methods.
What is Collation Collation is a kind of sort order. There are majorly 3 types of sort orders, namely: i.) Dictionary case insensitive ii.)Dictionary - case sensitive
The PROJECT operation The project operation is used to choose the records with specified attributes as discarding the others based on some related criteria. This is denotes as ∏
Explain the Cartesian product: The Cartesian product operation does not need relations to union-compatible. The meaning of this is that the involved relations may have dissim
Sequential File Organisation The most necessary way to organise the collection of records in a file is to use sequential Organisation. Records of the file are stored in series
Dirty Reads: T10 reads a value which is updated by T9. This update has not been committed and T9 aborts. T9 T10 Value of x old value = 200
Home based assignment Consider an ORDER table with the following attributes: • Order Number (ONo),Customer Number (CNo),Customer Name (CNa),Item Number (INo),Unit Price (UP), Quant
Explain the Exec statement in SQL Ans: Exec statement has the structure EXEC SQL END-EXEC Embeded SQl statements are of a form identical to non embedded SQL statem
An important first step to the statistical analysis of data is to "get to know your data". The following tasks should contribute to this. (a) To the right of the dataset cons
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