2. ETL is everything What is ETL? ETL Stands for: Extract – Transform – Load ETL is the set of processes which are done in-order to generate the data what is to be stored in a database/used for analysis
3. ETL is everything ETL Explained Let us consider Tom who wishes to create a database of famous pop albums. The Process that he undertakes under an ETL model will be as follows: Extract Data TransformData Information from Album DVDs Data Warehouse Load Data A Data warehouse is defines as a data repository from which retrieval is very quick Internet Books Info from friends
4. Migrating a Database An Important feature in Database systems is the migration of a database It is defined as the process of porting data from one platform/application in one format to another of a same/different format The Process of migration is quite simple: Understand a database and its properties Understand the differences between the source and the destination system Make the pre-migration changes in the source data Migrate from source to destination via automation/manual entry Make the post-migration changes in the destination data
5. Migrating a Database Illustration: Consider that a school ‘Hermione Internationals’ upgrades its management system from a Foxpro DBMS to SQL Server 2008 system. The Database contain the same data(student information) but the format and organization of stored-data will differ. Extract values from DB Feed data into DB Integrate DB into Application Isolate DB
6. Inserting into a Database After creating the structure of a database, the next step is to insert values into it. The Insertion of values must be done with care. The Important things which are to had in mind are: The Data type of value that is inserted should match with the data type of the field The Size of the value inserted must fall within the size which is designated for a particular field while designing of the table.
7. Inserting into Database The SQL command to insert into the database is the insert into command Syntax: insert into <table_name> values (<values>,..) For example, consider a database maintained by a kid named ‘Jessy’. The database contains information about the cartoons that she watches on Tv. Table name: cartoon
8. Inserting into Database Now suppose Jessy starts watching a new show ‘Laughs and Gags’ on Pogo Channel, she needs to insert this into her database SQL Command: insert into cartoon values(‘Laughs and Gags’,’Pogo’,’4PM: Weekends’, null); Jessy has just started watching the series and can decide on the rating after some-time only. Hence, the field is left as NULL The Order in which the values are given is the order in which they were designed
9. Updating a Database Now, suppose Jessy has become a fan of ‘Laughs and Gags’ show and wants to give it a rating of 100, she musupdate her database. The SQL syntax for updation is: Syntax: update <table_Name> set <field_Name>=<new_Value> where <condition> For example, consider the database maintained by ‘Jessy’. Null
10.
11. For string matching, use the ‘like’ keyword. Here, wild card characters(% and _)% -character represents a group(or single) of characters _ -character represents a single character Illustration: To Update cartoons whose names start with the letter ‘a’ must be given as Update cartoon set rating=100 where cartoonName = ‘a%’
12. Updating a Database Illustration: To Update cartoons whose names start with the letter ‘a’ and the name must of 3 characters in length: Update cartoon set rating=100 where cartoonName = ‘a__’
