Jahziah.
العربية

STUDY GUIDE · GKU 2

Data and information: databases and business analytics study guide (Information Systems)

An organisation runs on two kinds of data work. The first keeps the records right: a relational database that stores orders, payments and customers, answers questions in SQL, refuses data that breaks the rules, lets hundreds of users change it at once without losing anyone's update, and lets only the right people see it. The second turns records into decisions: framing a business question as a data question, exploring and summarising the data, choosing the analytics task that fits, scaling the work out when the data no longer fits one machine, and drawing the result so that a manager reads it correctly at a glance. This unit follows that order. One small online shop, with customers, orders and products, runs through the database sections so that every query result can be checked by hand.

Continue in the app

Structured by the official ETEC subject standard for this topic: every listed topic and learning outcome, with formulas, figures and worked examples. The full sections are available to members in the app.

SKU 2.1 · Data and information management

  1. Relational databases and SQL queries

    Tables, keys and the four kinds of SQL statement; how a SELECT is evaluated, clause by clause; joins, grouping and aggregates, and the NULL and counting traps that decide most exam answers.

  2. Designing relational databases: integrity constraints and normalisation

    How a schema refuses bad data (key, NOT NULL, CHECK and foreign-key constraints), what functional dependencies are, and how to normalise a table to third normal form without losing information.

  3. Programming and securing databases: views, functions, triggers and privileges

    Logic that lives inside the database (views, stored functions and procedures, triggers), and the controls that keep data from the wrong people: authentication, GRANT and REVOKE, roles, least privilege, parameterised queries against SQL injection, encryption and auditing.

  4. Concurrency control: locking, optimistic validation and their trade-offs

    Why concurrent transactions lose updates, how two-phase locking prevents it at the price of waiting and deadlock, how optimistic and multiversion schemes avoid waiting at the price of aborts, and how to choose for a given workload.

  5. Non-relational (NoSQL) data models

    Key-value, document, wide-column and graph stores: what each is good at, how to model data around the queries an application runs, and what replication across servers does to consistency (CAP, BASE, eventual consistency).

SKU 2.2 · Data and business analytics

  1. Computational thinking, data science and the analytics tasks

    The four habits of computational thinking applied to data, the data-science lifecycle, how to turn a business question into a data problem, the core analytics tasks (classification, clustering, optimisation, recommendation) and why accuracy alone can mislead.

  2. Exploratory data analysis and choosing a chart

    Exploratory analysis from the first question to the value proposition: checking quality and missing values, summarising centre and spread, finding outliers with quartiles, measuring association, and matching each question to the chart that answers it, with the Python (pandas) commands that do it.

  3. Big data tools: HDFS, MapReduce, Spark and relational operations at scale

    What makes data "big", how HDFS splits and replicates files, how MapReduce and Spark move the computation to the data, and how selection, projection, grouping and joins are carried out on a cluster, with the network cost that decides between plans.

  4. Human perception and honest, readable data graphics

    How the eye and brain read a chart: preattentive features, Gestalt grouping, the accuracy ranking of visual encodings, Stevens' law for area, colour scales and colour-vision deficiency; and the design rules (lie factor, data-ink, a zero baseline for bars) that make a graphic both accurate and pleasant to read.

MORE INFORMATION SYSTEMS GUIDES

All study guides

Read the full guide beside your practice questions.

Open the app