data structures

• Data structure

  A related set of data items stored under a single identifier. Examples are records and arrays.
• Array

  A data structure that stores many data items of the same data type, can be one-dimensional, two-dimensional or more. (In Python we use a list for this)
• Identifier

  The name we give a variable or data structure in an algorithm. In temp ← 25 the identifier is temp
• Value


  The data item that is stored under an identifier. In temp ← 25 the value is 25.
• One-dimensional

  An array that represents a single list of values, e.g. [25,27,19,20,22]
• Two-dimensional

  An array that represents a grid of values, such as codes for the pieces on a chessboard, or the intensity of pixels on a computer screen
• gameboard[0][0]

  The pseudo-code to return the contents of row 0 column 0 of a 2D array called gameboard
• Record

  A collection of related data items called fields, often stored as a row in a database, it represents something in the real world like a person or product
• Field

  A data item in a record, often shown as a column in a database. For example "Name" or "Age". It has a single data type
• Table

  A collection of records that share the same fields. Usually a complete set of related information about multiple items, such as "students" or "products"
• Database

  An organised collection of data made up of tables of records which can be easily updated or queried. Often we use SQL to do this.
• Query

  A command that searches a database and returns the data we are looking for. Often written in SQL
• SQL


  Popular language for accessing databases, short for Structured Query Language
• Chessboard

  An abstraction of this would be best stored in a two-dimensional array
• Shopping list

  This can be stored in a one-dimensional array because it is a single list of strings
• Student

  All the data about this subject could be stored in a record data structure