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In this part, we will see how one can create simple tables.

In the last parts we have looked into how to view the data in the tables and how to modify them. But for all this to happen, there must be a structure in the database that can hold all the rows. Tables define the structure of how many elements each row must contain.

For example, the table definition of the table emp_data that we have been using would something as follows:

Data Modification Tasks

Again, for sake of illustration, I would assume that the following table exists in the database:

The data retrieval using SQL is done using a SELECT statement.

For sake of illustrations consider the following imaginary EMP_DATA table:

SQL is Structure Query Language. It is a way of communicating with the DataBase Management System (DBMS). A DBMS has the stored data in a particular format, and has tools that retrieves and manipulates this data. The SQL communicates to the DBMS on what task requires to be done by it.

There are a lot of different DBMS. The earlier ones started of by storing data in simple flat files with each record stuffed in a line and each column of data separated by comma or other ASCII character. Then, they evolved into what are called as RDBMS - relational DBMS. In these databases, the data is organized into tables that have one or more columns. Each record is stored as a row, with each of the data split into the different columns.

The tabular structure forms the basis for many of the SQL instructions. The SQL instructions may be grouped as:

• Data Retrieval Tasks
• Data Modification Tasks and Control Tasks
• Data Definition Tasks

The term Database, in these days are generally used with respect to Computer Science, but they did exist earlier, in physical forms like files (real ones) and tabbed folders stored in cabinets of a warehouse like structure. This article though would be looking at the evolution of Database in terms of Computer Science.

There are various sources to this article and mention of all of them would take up a lot of space. Moreover, most of the information is known publicly with in the circles of the technically adept.