Provided by GeekGirls.com
database: A collection ofrelated information stored in a structured format. Database is sometimesused interchangeably with the term table. Technically, they�redifferent: A table is a single store of related information; a database canconsist of one or more tables of information that are related in someway. For instance, you could track all the information about the students in aschool in a students table. If you then created separate tables containingdetails about teachers, classes and classrooms, you could combine all fourtables into a timetabling database. Such a multi-table database is called a relationaldatabase.
You are watching: A field that uniquely identifies each record
data entry: The process of getting information into adatabase, usually done by people typing it in by way of data-entry formsdesigned to simplify the process.
dbms: Database management system. A program which letsyou manage informationin databases. Lotus Approach, Microsoft Access and FileMakerPro, for example, are all DBMSs, although the term is often shortened to�database�. So, the same term is used to apply to the program you use to organizeyour data and the actual data structure you create with that program.
field: Fields describe a single aspect of each member of a table. A student record, for instance, mightcontain a last name field, a first name field, a date of birth field and so on.All records have exactly the same structure, so they contain the same fields.The values in each field vary from record to record, of course. In somedatabase systems, you�ll find fields referred to as attributes.
flat file: A database that consists of asingle table. Lightweight database programs such as the databasecomponent in Microsoft Works are sometimes called �flat-file managers� (or listmanagers) because they can only handle single-table databases. More powerfulprograms, such as FileMaker Pro, Access, Approach and Paradox, can handlemulti-table databases, and are called relational database managers, or RDBMSs.
foreign key: A key used in one table to represent the value of a primary key in a related table.While primary keys must contain unique values, foreign keys may have duplicates.For instance, if we use student ID as the primary key in a Students table (eachstudent has a unique ID), we could use student ID as a foreign key in a StudentCoursetable: as each student may do more than one course, the student ID field in theStudentCourse table (often shortened to StudentCourse.student ID) will holdduplicate values.
index: A summary table which lets you quickly look up thecontents of any record in a table. Think of how you usean index to a book: as a quick jumping off point to finding full informationabout a subject. A database index works in a similar way. You can create anindex on any field in a table. Say, for example, you havea customer table which contains customer numbers, names, addresses and otherdetails. You can make indexes based on any information, such as the customers�customer number, last name + first name (a composite index based on more thanone field), or postal code. Then, when you�re searching for a particularcustomer or group of customers, you can use the index to speed up the search.This increase in performance may not be noticeable in a table containing ahundred records; in a database of thousands of records it will be a blessing.
key field: You can sort and quickly retrieve information from a database by choosing one or more fields to act as keys.For instance, in a students table you could use a combination of the last nameand first name fields (or perhaps last name, first name and birth dates toensure you identify each student uniquely) as a key field. The database programwill create an index containing just the key field contents.Using the index, you can quickly find any record by typing in thestudent�s name. The database will locate the correct entry in the index andthen display the full record.
Key fields arealso used in relational databases to maintain thestructural integrity of your tables, helping you to avoid problems such asduplicate records and conflicting values in fields (see primary key and foreign key).
normalization: The process ofstructuring data to minimize duplication and inconsistencies. The processusually involves breaking down a single table into two or moretables and defining relationships between those tables. Normalization isusually done in stages, with each stage applying more rigorous rules to thetypes of information that can be stored in a table. While full adherence to normalizationprinciples increases the efficiency of a particular database, the process canbecome so esoteric that you need a professional to create and understand thetable design. Most people, when creating a database, don�t need to go beyondthe third level of normalization, called third normal form.
primarykey: A field that uniquely identifies a record in a table. In astudents table, for instance, a key built from last name + first name might notgive you a unique identifier (two or more Jane Does in the school, forexample). To uniquely identify each student, you might add a special Student IDfield to be used as the primary key.
query: A view of your data showing information from one or moretables. For instance, you could query the Students database asking “Showme the first and last names of the students who take both history and geographyand have Alice Hernandez as their advisor” Such a query displaysinformation from the Students table (firstname, lastname), nadechworld.com table(course description) and Advisor table (advisor name), using the keys (studentID, course ID, advisor ID) to find matching information.
rdbms: Relational database management system. A program which lets youmanage structured information stored in tables and which can handle databases consisting of multiple tables.
record: A record contains all the information about a single �member� of atable. In a students table, each student�s details (name, dateof birth, contact details, and so on) will be contained in its own record.Records are also known as tuples in technical relational database parlance.
relational database: A database consisting of more than one table. In a multi-tabledatabase, you not only need to define the structure of each table, you alsoneed to define the associations between each table in order to link thosetables correctly.
report: A form designed to print information from a database(either on the screen, to a file or directly to the printer).
SQL: Structured Query Language (pronounced sequel inthe US; ess-queue-ell elsewhere). A computer language designed to organizeand simplify the process of getting information out of a database in a usableform, and also used to reorganize data within databases. SQL is most often usedon larger databases on minicomputers, mainframes and corporate servers.
table: A single store of related information. A table consists ofrecords, and each record is made up of a number of fields. Just to totally confuse things, tables are sometimes called relations.You can think of the phone book as a table: It contains a record for eachtelephone subscriber, and each subscriber�s details are contained in threefields � name, address and telephone.