Data and Information Management
From data to information
Data becomes information when it is organised and given context for a purpose. Candidates must understand the data hierarchy (character, field, record, file/table, database), data types and field properties such as validation rules, default values and primary keys. Learn relational database concepts: tables, primary keys (uniquely identify a record), foreign keys (link to another table) and relationships (one-to-one, one-to-many, many-to-many). Know why normalisation reduces redundancy and update anomalies.
Querying and design
Be able to interpret simple SQL statements (SELECT, FROM, WHERE, ORDER BY) and explain what a query returns. Understand the purpose of a data dictionary, and how forms, reports and queries support users. Know the difference between validation (data is reasonable - e.g. a date rule) and verification (data matches the source - e.g. double entry or proofreading).
Traps to watch
A common trap is choosing a field as a primary key when it could repeat or be null - a primary key must be unique and not null. Another is confusing a foreign key with a primary key: the foreign key in one table is the primary key in another. Questions may ask you to spot redundancy in an unnormalised table; look for repeated groups of data.
Worked example
In a library database, the Member table's primary key is MemberID. The Loan table stores MemberID as a foreign key, creating a one-to-many relationship (one member, many loans). Rule of thumb: if a value can appear many times in the child table but only once in the parent, it is a foreign key in the child.