Traditional Culture Encyclopedia - Traditional culture - What are the relational operations in the database?
What are the relational operations in the database?
It should be divided into two categories: 1. Traditional relational operation of mathematical sets II. The unique relational operation of database. The relational database itself is a two-dimensional table, which is equivalent to an ordered linked list and can also be regarded as a collection in mathematics. (1) The operation between tables can be regarded as the operation between sets, and most arithmetic operations such as AND, OR, NOT and XOR are supported. (2) "Projection operation": that is, the operation on one column (field) or multiple columns of the database.
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