33 terms

IGCSE Databases

A set of 30 technical terms covering the vocabulary of the IGCSE ICT database unit.
Contains a combination of letters and numbers. For example, a UK postcode: "NE4 3AQ", a street address containing the house number: "4 Willow Drive".
A field that can only have two possible values. For example: "on/off", "true/false", "male/female".
Calculated field
Calculated fields can be used to add totals, averages etc to fields displayed in a report. You might, for example, want to display the total value of current stock by using a calculated field.
Numerical data formatted as currency, usually with symbol and two decimal places. For example: "$499.99", "€10.00", "¥250.00"
Data Types
Categories of data that are used to help classify it to ensure consistency. Examples include: alphanumeric, numeric, currency, date/time, lookup & Boolean.
A database is a collection of related information organized in a logical way for rapid search and retrieval.
Date stored in one of several formats set by the database creator. For example: "19-Jan-04", "14/04/07". Note that we always use British formatting: DD/MM/YY
Design view
A view in which you can add, edit, and delete fields from the table, change field types and descriptions, set a primary key, and more.
An entity is a concept, person, place or thing about which can be collected. For example: student, address, engine capacity.
Fields provide the categories for the details describing each record. Example: Name, address, and phone number would be fields.
Flat-file database
A database that contains only one table.
Foreign key
A foreign key is a key field from another table that has been used to create a relationship.
A form is a data entry tool, used to enter data into a table in a simple, clear way. Forms may include checkboxes, drop-down lists and other features linked to validation rules to avoid making mistakes.
Junction table
Junction tables are created to avoid many-to-many relationships. It contains foreign keys from two associated tables with a one-to-many relationship with each. For a library system, a 'loans' table may be added to link the 'borrowers' and 'books' tables and avoid the large scale duplication of data that would happen otherwise.
Creating a set of labels based on data in a table. Fields can be inserted and formatted. These could be address labels for envelopes, stickers for CDs that show the songs, etc.
Field is entered from a pre-existing list of options set by the database creator. For example, personal titles: "Mr, Mrs, Miss, Ms", days of the week or available car colours.
When any record in table A can match more than one record in table B and vice-versa, this is a many-to-many relationship. Many readers may borrow many books in a library database. This kind of relationship can be quite messy, however, and can usually be avoided by adding a junction table.
Numerical data stored as an integer or decimal. For example: "200", "49.534".
When each record in table A can match more than one record in table B, this is a one-to-many relationship. A mother may have one or more children, but they only have one mother.
When every record in table A matches only one record in table B, this is a one-to-one relationship. An example could be married couples. One husband has one wife & vice-versa.
Parameter value query
A query where the term being searched for is entered in a dialog window, so the search term can change each time the query is run.
Primary key
A field that uniquely identifies each record in a table.
A query is a search, or request for information from a database against set criteria. Simple queries contain only one criterion in one field, for example all R&B songs in a music database, or horror movies in a DVD database, whereas complex queries contain more than one, for example all brown cars made by Mitsubishi in 2012.
Query operators
Used in criteria to compare values. Operators include =, <, >, <=, >=, <>, and, or, not, between.
A record is a set of related fields in a database about a person or thing. A personnel database might contain a record that contains: "Timmy Chen", "155 Tianmu East Road", "Taipei". A car database might contain a record that includes: "Ford", "Focus", "2013", "2L engine".
Referential integrity
Enforcing referential integrity forces the database to ensure that data is linked as-intended. This option is used to enforce one-to-one, one-to-many & many-to-many relationships between tables. This can prevent the accidental duplication of data.
Relational database
A database that contains more than one table. The tables are linked by a relationship based on primary keys.
A report is a document that presents information in a clear, professional way.
Runtime query
A query where extra data is calculated when the query is run, most often in a new field. This is often for numerical data, for example adding a Profit field by subtracting the values in the Costs field from the values in the Income field.
To organize data alphabetically or in numerical order. To sort in ascending order is from smallest to largest (A to Z and 0 to 9). To sort in descending order is from largest to smallest (Z to A and 9 to 0).
Tables contain sets of records in a database. These can be "standalone", or can be linked to other tables by the use of relationships.
Wildcard searches find results similar to the search operator. For example, searching for "Ch" in a student database might display records such as Chang, Chen, Chretien & Christophe. Searching for "love" in the song name field of a CD database would display songs with the word love in the title. Searching for "459" in the registration number field of a car database would display any cars with a registration number ending in 459.
A predefined group of settings for creating a new table, query or report, including data types, validation rules, formatting, etc.