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Views can represent a subset of the data contained in a table. Consequently, a view can limit the degree of exposure of the underlying tables to the outer world: a given user may have permission to query the view, while denied access to the rest of the base table. [2] Views can join and simplify multiple tables into a single virtual table. [2]
Spaghetti code is a pejorative phrase for difficult-to-maintain and unstructured computer source code.Code being developed with poor structure can be due to any of several factors, such as volatile project requirements, lack of programming style rules, and software engineers with insufficient ability or experience.
The SQL standard defines embedding of SQL as embedded SQL and the language in which SQL queries are embedded is referred to as the host language. A popular host language is C. Host language C and embedded SQL, for example, is called Pro*C in Oracle and Sybase database management systems, ESQL/C in Informix, and ECPG in the PostgreSQL database ...
The builder pattern is a design pattern that provides a flexible solution to various object creation problems in object-oriented programming.The builder pattern separates the construction of a complex object from its representation.
The following example represents an n-to-1 relationship between movies and their directors. It is shown how user-defined Python classes create corresponding database tables, how instances with relationships are created from either side of the relationship, and finally how the data can be queried — illustrating automatically generated SQL ...
Conjunctive queries without distinguished variables are called boolean conjunctive queries.Conjunctive queries where all variables are distinguished (and no variables are bound) are called equi-join queries, [1] because they are the equivalent, in the relational calculus, of the equi-join queries in the relational algebra (when selecting all columns of the result).
Type 1 that calls native code of the locally available ODBC driver. (Note: In JDBC 4.2, JDBC-ODBC bridge has been removed [15]) Type 2 that calls database vendor native library on a client side. This code then talks to database over the network. Type 3, the pure-java driver that talks with the server-side middleware that then talks to the database.
Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL . [ 1 ] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.