Nick Marshall – WGU Note Repository

12 pages 3.1 Introduction to SQL Structured Query Language Structured Query Language (SQL) is a high-level computer language for storing, manipulating, and retrieving data in a relational database. SQL, pronounced “ess-que-el” or “see-qual”, is the language used by database designers and database users to interact with relational database systems. Though the SQL language has been standardized, a…

8 pages 2.1 Relational model Database models A database model is a conceptual framework for database software. Leading database models of the 1960s, such as the hierarchic and network models, optimized processing speed at the expense of programmer productivity. As computer speed increased and programs became more complex, programmer productivity became paramount. A simpler approach was needed. E.…

11.1 Basic debugging Debugging A program is a series of instructions (aka statements) a computer executes to perform a calculation, like a recipe is a series of instructions a chef executes to make a meal. Programs are hard to write and often have problems, like displaying wrong output. In a program, a problem’s cause is called a bug, and troubleshooting…

10.1 Troubleshooting: Hypotheses and tests Introduction to troubleshooting Mechanical and electronic systems sometimes have problems. Ex: A lamp may suddenly turn off, a smartphone won’t charge, or a car won’t start. In everyday life, users encountering a problem must find and fix the underlying cause. But, many users don’t follow a systematic process for finding causes,…

9.1 Language survey Compiled vs. interpreted languages Many kinds of programming languages have evolved, serving different purposes. One kind is a compiled language. A program written in a compiled language is first converted by a tool (compiler) into machine code, which can run on a particular machine. Examples include C, C++, Java, and C#. In contrast, an interpreted language (aka scripting…

8.1 Software design processes System development life cycle A 4-bedroom house can be built using different arrangements of phases. For one house, first a 4-bedroom blueprint might be created, and then the 4-bedroom house built per that blueprint. For another house, first a 1-bedroom blueprint might be created, then that 1-bedroom house built (and moved into),…

7.1 Algorithms Problem solving and algorithms Programs solve problems. Before writing a program, a programmer must first create an algorithm to correctly solve the given problem. An algorithm is a sequence of steps that solves a problem, generating correct output for any valid input values. Ensuring an algorithm’s correctness is a key job for a programmer. Introduction to…

18 pages 10 labs 6.1 User-defined function basics Basics of functions A function is a named list of statements. A function definition consists of the new function’s name and a block of statements. The function’s name can be any valid identifier. A function call is an invocation of a function’s name, causing the function’s statements to execute. A local variable is a variable declared…

10 pages 5.1 Array concept (general) A typical variable stores one data item, like the number 59 or the character ‘a’. Instead, sometimes a list of data items should be stored. Ex: A program recording points scored in each quarter of a basketball game needs a list of 4 numbers. Requiring a programmer to declare 4 variables is…

Loop concept People who have children may be familiar with looping around the block until a baby falls asleep. Parents may be familiar with this scenario: Driving home, baby is awake. Parents circle the block, hoping the baby will fall asleep. After first loop, baby is still awake, so parents loop again. After second loop,…