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A primary key is a unique identifier for a discrete object on a table, and a secondary key provides a second reference point for objects whose primary keys do not adequately distinguish them for reference purposes. The t... More »

Secondary metabolites produced by plants are chemicals that have no defined role in the plant's metabolism, including growth, photosynthesis, reproduction and other primary functions. Many secondary metabolites produced ... More »

A primary source refers to documentation or material presented by parties that were directly present or involved in the referred subject, while a secondary source refers to documentation derived from the opinion or views... More »

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In procedural programming, a program is divided into portions called functions, while in object oriented programming, the program is divided into portions called objects. Another key difference is that object-oriented pr... More »

In the Java programming language, a Map is an object that connects keys to values. It works like a mathematical function, so each key can only link to one value, and each key must be unique. More »

An object-oriented model uses objects containing stored values to unite the application and database development, while a relational model uses relations to construct data. The rational model is used to create grid-like ... More »

An identifier is a name that identifies an object or group of objects. The object or group of objects may be ideas, physical things or physical substances. An identifier can be a number, word, symbol, letter or mixture o... More »