5.1. Introduction
In Chapter 4, we have discussed the relational query based on relational algebra and relational calculus. The relational algebra and calculus provide a powerful set of operations to specify queries. This forms the basis for the data manipulation (query) language component of the DBMS. But, such languages can be expensive to implement and use. In reality, data manipulation languages generally have capabilities beyond those of relational algebra and calculus. All data manipulation languages include capabilities such as insertion, deletion, modification of commands, arithmetic capability, assignment and print command, aggregate functions and so on, which are not part of relational algebra or calculus.
Queries in a relational language ...
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