We are going to explore Relational Structure
- Relational Data
- Normalization : Minimize data duplication and enforce data integrity. Rules for normalization:
- Separate each entity into its own table
- Separate each discrete attribute to its own column
- Uniquely identify each row using primary key
- Use Foreign key column to link related entities
SQL stands for Structured Query Language, and is used to communicate with a relational database. It's the standard language for relational database management systems. SQL statements are used to perform tasks such as update data in a database, or retrieve data from a database.
Transact-SQL (T-SQL). This version of SQL is used by Microsoft SQL Server and Azure SQL services.
pgSQL. This is the dialect, with extensions implemented in PostgreSQL.
PL/SQL. This is the dialect used by Oracle. PL/SQL stands for Procedural Language/SQL.
Virtual table based on result of SELECT query.
CREATE VIEW Deliveries AS SELECT o.OrderNo, o.OrderDate, c.FirstName, c.LastName, c.Address, c.City FROM Order AS o JOIN Customer AS c ON o.Customer = c.ID;
- Stored Procedure
Defines SQL statements that can run on command.
Stores program logic when working with data.
CREATE PROCEDURE RenameProduct @ProductID INT, @NewName VARCHAR(20) AS UPDATE Product SET Name = @NewName WHERE ID = @ProductID;
It helps to search data in a table.
Index has a copy of column in sorted order, with pointer corresponding row in a table.
Quickly scan the data.
We can create many index on a table.
Index consume storage space.
Thanks for reading <3