Column relational database

The characteristic of a relational database model is the organization of data in different tables that have relationships with each other. A table is a two-dimensional consti uction of rows and columns. All the entries in one column have an equivalent meaning (c.g., name, molecular weight, etc. and represent a particular attribute of the objects (records) of the table (file) (Figure 5-9). The sequence of rows and columns in the tabic is irrelevant. Different tables (e.g., different objects with different attributes) in the same database can be related through at least one common attribute. Thus, it is possible to relate objects within tables indirectly by using a key. The range of values of an attribute is called the domain, which is defined by constraints. Schemas define and store the metadata of the database and the tables. 

A database (or data base) is a collection of data that is organised so that its contents can easily be accessed, managed, and modified by a computer. The most prevalent type of database is the relational database which organises the data in tables multiple relations can be mathematically defined between the rows and columns of each table to yield the desired information. An object-oriented database stores data in the form of obj ects which are organised in hierarchical classes that may inherit properties from classes higher in the tree structure. 

Traditionally data, properties, information etc has been stored in files on computer disks. More recently, it has become common practice on Macintosh computers, when using Microsoft software or some UNIX applications, to use either extensions to the file name or the first few bytes in the file (or another file) to indicate some aspects of the data, for example that it is suitable for Microsoft Excel. While this approach is practical to indicate something about files containing columns of data, it is not appropriate to store information about the values in cells in spreadsheet or how it relates to data in other columns. This requires a relational database such as ORACLE, and for performance reasons the values in the cells may only be accessed via the ORACLE API (Application Programming Interface) or SQL (Standard Query Language), in other words, it is suggested that relational databases such as ORACLE should be viewed as sophisticated file systems which allow the values to be organised, efficiently stored, rapidly retrieved etc. 

Table 6. Typical Relational Database Columns used by Chem-X...

Relational database systems, both open-source and proprietary, rely on the DDL statements from SQL (CREATE, DROP, and ALTER) to perform schema evolution, though the exact dialect may vary from system to system (Tiirker 2000). So, to add an integer-valued column C to a table T, one uses the following syntax ... 

Chapter 7 introduces ways in which RDBMS can be used to handle chemical structural information using SMILES and SMARTS representations. It shows how extensions to relational databases allow chemical structural information to be stored and searched efficiently. In this way, chemical structures themselves can be stored in data columns. Once chemical structures become proper data types, many search and computational options become available. Conversion between different chemical structure formats is also discussed, along with input and output of chemical structures. 

The tables are formally called relations, referring to the mathematical set theory used in the original work on relational databases.1 In database theory, rows are called tuples and columns are called attributes of a tuple. The focus of this book is practical, so the common terms table, row, and column are used. The detail of using the SQL language to perform these operations is left to a later chapter of this book. 

A table is a collection of data in rows and columns. As with tables in a scientific publication, each row typically represents some entity, such as a molecule, and each column represents some attribute of the entity, such as the name, molecular weight, ionization potential, or other theoretical or experimental data measurement. A table in a publication is laid out for clarity to the reader. Spreadsheet programs typically include ways to control the layout and look of the table. Display and layout features are irrelevant in a relational database. 

A relational table has a name, chosen when it is created. Although any name is possible, the name typically reflects the nature or source of the data contained in the table. Each column must also have a name. Consider Table 2.1, called EPA since it was constructed from data provided by the Environmental Protection Agency.2 This table is readily understandable to any chemist. Each row contains information about one compound and each column contains a molecular attribute or property. In order to make it part of a relational database, a minimum of two things must be specified for each column the column name and the column data type. In this example, the column names are Name, Formula, MW, logP, and MP corresponding to the compound name, molecular formula, molecular weight, octanol-water partition coefficient, and melting point. The column name in a relational table is arbitrary but is usually representative of the data contained in the column. 

The nature of the data in each column must be specified by providing a data type. The data type must be one of a fixed set of types available in the relational database management system (RDBMS) being used. A discussion of several common RDBMS follows in Chapter 4. Some of the frequently used data types are... 

Sometimes, there is no value available for a particular column or a particular row. Rather than inventing a special value to represent this, such as 99999 for numeric or "" for text, the relational database provides a special null value. This should be used when a value is unknown or unavailable. When actual data becomes available, the null value can be updated. 

In a relational database, data in a column may be indexed. This is explained in a later section of this chapter. If the relational table contains an index, many operations on the table can be greatly accelerated. Indexing is not possible in most spreadsheet programs. 

To the user, the relational database consists of a collection of tables (or relations in the formal language of the model). Each table may be thought of as a matrix of values divided into rows and columns. Each row represents a record and is referred to as a tuple in the model. Each column is a field and is called an attribute in the model. Below are some simple tables for Employee and Department. 

The relational model is a modification of the individual record model that limits its data structures and thereby provides a mathematical basis for operation on records. Data structures in a relational database may consist only of relations, or field sets that are related. Every relation may be considered as a table. Each row in the table is a record or tuple. Every column in each table or row is a field or attribute. Each field or attribute has a domain that defines the admissible values for that field. 

Introducing fill boxes in the standard report made through RDS2 (Report Definition System). These fill boxes are 1 1 related with RDBMS (relational database management system) column names and will be filled at display time by interactive commands. 

The internal structure of a full-text database is significantly different from that of other types such as relational (row/column/table-oriented) or object-oriented databases. The domain of a full-text database is the indexing and storage of large amounts of textual data. Indexes based on words occurring in the text corpus, proximity operators to locate phrases and close spatial relationships between words, and probabilistic thesauri to define word, concept, and content clusters are important characteristics of this type of database. See Bibliographic Database Object-oriented Database Object-Relational Database Relational Database and Textual Database. 

A type of database which combines aspects of the classical relational database (rows, columns, tables) with features of object-oriented databases (support for data of unusual types or with inner structure, inheritance relationships, or user-defined functions which perform complex operations on data). See Full-text Database Object-oriented Database and Relational Database. 

One of the oldest types of database and still the most widespread. A relational database organizes the stored data items into tables in which the columns are fields of a specific type and the rows are data entries. The typical query language for relational databases is SQL (systems query language), which is powerful, well defined and, within the domain of the SQL standard, independent of the database vendor. See. Full-text Database Object-oriented Databa.se and Object-Relational Database. 

A CRO may also allow for the in-house introduction of specialized lipophilic scales by transferring routine measurements. While the octanol-water scale is widely applied, it may be advantageous to utilize alternative scales for specific QSAR models. Solvent systems such as alkane or chloroform and biomimetic stationary phases on HPLC columns have both been advocated. Seydel [65] recently reviewed the suitabihty of various systems to describe partitioning into membranes. Through several examples, he concludes that drug-membrane interaction as it relates to transport, distribution and efficacy cannot be well characterized by partition coefficients in bulk solvents alone, including octanol. However, octanol-water partition coefficients will persist in valuable databases and decades of QSAR studies. 

The dictionary relates symbolic names to the real world. So if I told you that fris is the name I use for my age and bee is how the age of the current British Prime Minister is referred to in my household, then you could find out whether fris > bee is true or false. If the model in Figure 2.16 were of a database, the dictionary would relate the model elements to tables, columns, and so on. 

There are further resources available for English translations of Japanese patent documents. Paterra, Inc., (http // www.paterra.com) is pleased to present the InstantM D service for Japanese patents on the internet. The InstantM D service retrieves the requested patent by number and rapidly provides a translated version which is rendered for download in a two-column formatted Acrobat PDF file. The system covers all Japanese Kokai (A documents) published after January 1, 1993 and aU granted Japanese patents (Toroku) published since May 27, 1996. New documents are entered into the system within 2 weeks of being published in Japan, hi a related development, Protys (http //www.protys.info/) provides a full text Enghsh database of the latest Japanese patents in a specialty current awareness database. 

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