A nice introduction to sql will begins by looking at databases in terms of what they are and why and when you want to use them ,how sql will links with databases and how it will be useful.
A brief history of databases:
In 1960’s IBM researches in particular automating data storage and indexing tasks that previously required a great deal of manual labor,so IBM made easier and cheapest computing services for indexing and storage available solution.
Although IBM was a leader in database research Honeywell information systems released a commercial product in 1976 based on same principles as IBM but it was separately designed without disturbing IBM’s work.
In 1980’s the first database systems built upon the SQL standard appeared from the companies ORACLE ,with Oracle Version 2, and later SQL/DS from IBM, as well as a host of othersystems from other companies.
What is a database ?
A database is defined as a one or more structured sets of persistent data ,usually associated with software to update and query the data.A simple databse might be a single file containing many records each of which contains the same set of fields where each field is a certain fixed width.Breaking this definition down into something more manageable, first it says that a database consists of structured sets of data, which means that a database contains collections of data.
Finally, the definition states that, as with the Access database example, a simple database might be just one file with many records with each record broken down into fields. But what are records and fields?
A field is a single item of data about a specific thing and the thing could be a person ,and the field could be a person’s DOB,ADDRESS,MOBILE NUMBER,etc.,All these fields referred to a specific thing then it will be a one record and collectively all records are in database or something in is known as a table .
Hopefully you get the idea that database is used to store ,update ,and retrieve data . one last thing is to metion the relational database, which is a database containing data organized and linked (related) to the tables each other ,Most database management systems these days are relational, termed relational database management system (RDBMS). These systems make storing data and returning results easier and more efficient,they allow different questions to be posed of the database—even questions the original designer of the database didn’t expect to be asked.