SQL is a programming language for Relational Databases. It is designed over relational algebra and tuple relational calculus. SQL comprises both data definition and data manipulation languages.
Using the data definition properties of SQL, one can design and modify database schema, whereas data manipulation properties allows SQL to store and retrieve data from database. This command adds an attribute in the relation article with the name subject of string type.
Relational Algebra Exercises
DML modifies the database instance by inserting, updating and deleting its data. DML is responsible for all forms data modification in a database.
These basic constructs allow database programmers and users to enter data and information into the database and retrieve efficiently using a number of filter options.
It is similar to the projection operation of relational algebra. In case more than one relation names are given, this clause corresponds to Cartesian product.
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