Introduction to C# and .NET

• C# is an object-oriented programming language by Microsoft and runs on the .NET Framework.
• C# is related to C++, Java and other languages from the C family.
• Version 1 of the language came out in 2002.
• .NET framework aids in the development of web, desktop, and web services applications.
• .NET core facilitates the creation of cross-platform cloud applications compatible with Windows, Mac, and Linux.
• The MAIN METHOD serves as the entry point for a C# application.
• Namespaces in C# help to organize code.
• Console.WriteLine("Creating my namespace");
• Constants are immutable values known at compile time.
• PascalCase should be used for class names and method names.
• camelCase should be used for method parameters and local variables.
• PascalCase should be used for constant names, constant fields, and local constants.
• Console.ReadLine(); is used to read user output.
• Object-oriented programming involves creating objects composed of both data and methods.
• A class serves as a template for objects, while an object is an instance of a class.
• Fields and methods inside classes are referred to as "Class Members".
• Objects inherit variables and methods from their class.
• Variables inside a class are called FIELDS.
• Access Modifiers define the accessibility of a member, class, or datatype in a program:

Access Modifiers

• Public: Accessible to all classes
• Private: Accessible only within the same class
• Protected: Accessible within the same class, or in a class that is inherited from that class
• Internal: Accessible only within its own assembly
• A Method is a function inside a Class that contains a series of statements.
• Property: A member of a class in C# that is used to set and get the data from a data field.
• Accessors: Special methods used to set and get the values from the underlying data member of a class.
• A set accessor contains a fixed variable named value.
• A constructor is a special method that is used to initialize objects.
• Encapsulation is the wrapping up of data and information under a single unit.

Advantages of Encapsulation

• Data Hiding
• Increased Flexibility
• Reusability
• Testing
• The PUBLIC keyword is an access modifier that specifies accessibility for other classes such as Program.
• MS SQL Server is a Relational Database Management System (RDBMS) developed by Microsoft.
• Relationships in SQL tables define how tables are connected.
• Structured Query Language is a standardized programming language to manage and manipulate relational databases.

SQL Clauses/Keywords

• WHERE clause: Filters records and specifies conditions for a query
• ORDER BY clause: Sorts the result set of a query by one or more columns
• DISTINCT keyword: Removes duplicate values from the result set and returns the number of rows that match a specified condition
• SUM: Calculates the total sum of a numeric column
• MAX: Returns the maximum value from a numeric column
• MIN: Returns the minimum value from a numeric column
• GROUP BY clause: Groups rows that have the same values in specified columns into summary rows
• HAVING clause: Filters the results after GROUP BY has been applied

More DBMS Information

• A correlated subquery is a subquery in SQL that refers to values from the outer query.
• Full-Text Search is a database technique to retrieve records.
• JOIN is used in SQL to combine rows from two or more tables based on a related column.
• Right Joints select all the columns in the Right table with matching records from the left table.
• UNION operation combines the results of two queries and removes duplicate rows.
• INTERSECT operation returns only the rows that are present in both queries.
• EXCEPT operation returns rows from the first query that are NOT in the second query.

Core principles include:

• Data Integrity
• Avoiding Redundancy
• Normalization
• Entity Relationships
• Use of Constraints
• Scalability and Performance
• Entity relationship (ER) Modeling is a visual approach to representing the structure of a database by identifying and defining the different entities within the data and how they are related.
• Entity Relationship Cardinality (ERD) defines the number of instances of one entity that can be linked to the number of instances of another entity.
• A FOREIGN KEY (FK) is a column or combination of columns that establishes and enforces a link between the data in two tables.
• Constraints limit the type of data that can go into a table.
• Normalization organizes data efficiently within tables.
• Denormalization is also the method which is used in a database. It is a technique to quickly combine data.

Primary Normalization Goals

• Minimize redundancy
• Improve data integrity
• Enhance data flexibility

Relational Database Design Principles

• These serve as guidelines for organizing data in tables to ensure data integrity and efficiency
• Data Integrity ensures accuracy and consistency, like primary key uniqueness
• Avoid Data Redundancy by storing data once and referencing it
• Scalability and Performance optimize queries and updates
• Entity Relationships, use ER diagrams
• Normalization applies rules to structure data to reduce redundancy