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Lesson 11 - Sub Programs
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Lesson 11 - Sub programs
E- LEARNING
Revise, Recap, Review
Objectives
3 commands used in SQL
2 examples of utility software
1 SQL statement to return all Jaguar 'make' cars from the table 'Cars'
Lesson Objectives
To know the difference between a function and a procedure
To know the advantages of using sub programs
To use sub programs to solve a problem
Sub programs
Theory
A mini program within your program
They SAVE TIME if we use repeated code in our program
Type the code out once and give it a name
When you want to use that block of code you just type the name
Other advantages
As well as saving time, sub programs:
+Make programs easier to edit once created
+Help debug errors
+Create a more logical structure to our code
Functions and procedures
Procedures are blocks of code stored under one name
Called by typing their name - sometimes we also pass an argument to them
With parameter
Functions
VERY similar, but functions ALWAYS return a value back to be used in the main program
Functions always take at least one parameter
When calling a function we assign it to a variable - otherwise the value returned is lost!
Functions
Local or Global?
Variables can be local or global
Any variable used within a sub program is local and can only be called within itself - if you try and print it in the main.....ERROR: NOT DEFINED!
This means you can use the same variable name as other local variables without any issues
Global
Global variables can be used anywhere in the program
We can declare a global variable using the global key word
This means that they are accessible from both the main body and the sub programs
Task
Task
Write a function takes two strings and joins them together with a space in between them.
Call your function and print out the result in the main program