SQL Background

• SQL the Structured Query Language
• Read the last of paragraph 2 page 37.
• Endorsed by ANSI (American National Standards Institute)
• And by ISO (International Organization for Standardization)
• It is an evolving language
• Recent updates include support for XML.
• SQL:2008 is the 2008 standard of SQL.
• It is a data sublanguage
  • Only has the commands needed for creating, manipulating and extracting information from a database.
  • Sometimes referred to as a 4GL
• The language consists of a number of pieces:
  • DDL: a Data Definition Language
    • Used for creating tables, relationships and other structures
    • We will discuss this in Chapter 7.

    • create table ORDER_ITEM ( 
             OrderNumber Int NOT NULL, 
             SKU Int NOT NULL, 
             Quantity INT NOT NULL, 
             Price Decimal(10,2) Not NULL, 
             ExtendedPrice Decimal(10,2) NOT NULL, 
             Constraint Order_ItemPK Primary Key (SKU, OrderNumber), 
             Constraint Order_ItemFK1 Foreign Key(SKU) 
                       References SKU_DATA(SKU), 
             Constraint Order_ItemFK2 Foreign Key(OrderNumber)
                       References RETAIL_ORDER(OrderNumber));
      
      	    

  • DML: a Data Manipulation Language
    • Used to query, insert, modify and delete data.
    • We will discuss this now and in Chapter 7.

    • insert into ORDER_ITEM 
             (OrderNumber, SKU, Quantity, Price, ExtendedPrice) 
             values (1000, 201000, 1, 300, 300);
      	    

  • SQL/Persistent stored modules (SQL/PMS): Add programming capabilities to SQL
  • Aganin, Chapter 7.
• "SQL is ubiquitous"
• "SQL programming is a critical skill."