What are Tables? How to make Table?

What are Tables?

• Tables are the basic structure where data is stored in the database.
• Tables are divided into rows and columns.
• Each row represents one piece of data.
• Each column can be thought of as representing a component of that piece of data.
• For example: If we have a table for recording customer information, then the columns may include information such as First Name, Last Name, Address, City, Country, Birth Date, and so on. As a result, when we specify a table, we include the column headers and the data types for that particular column.

So what are data types?

• Typically, data comes in a variety of forms.
• It could be an integer such as 1, 2, 1002, -2002 etc.
• It could be real number. The real numbers include both rational numbers, such as 42 and −23/129, and irrational numbers, such as pi and the square root of two
• It could be a string such as 'sql', 'my name is burhan'
• It could be a date/time expression such as '2000-JAN-25 03:22:22'
• It coold be in binary format.

Note:

• When we specify a table, we need to specify the data type associated with each column. For example we will specify that 'First Name' (the column of any table) is of type char(50) - meaning it is a string with 50 characters).
• Many database tools allow you to create tables without writing SQL, but given that tables are the container of all the data.
• SQL is a standard language for accessing and manipulating databases.
• You can use SQL to access and manipulate data in MySQL, SQL Server, MS Access, Oracle, Sybase, DB2, and other database systems.

How to make Table?

A table is look like:

P_Id	LastName	FirstName	Address	City
1	Hansen	Ola	Timoteivn 10	Sandnes
2	Svendson	Tove	Borgvn 23	Sandnes
3	Pettersen	Kari	Storgt 20	Stavanger

The table above contains three records (one for each person) and five columns (P_Id, LastName, FirstName, Address, and City).

So, if we are to create the customer table specified which have First Name, Last Name, Address, City, Country, Birth Date. So we would type in:

CREATE TABLE customer (First_Name char(50),Last_Name char(50), Address char(50), City char(50), Country char(25), Birth_Date date);

here:
* "customer" is table name.
* "CREATE TABLE" is a key word use to make a new table.

• Sometimes, we want to provide a default value for each column.
• A default value is used when you do not specify a column's value when inserting data into the table.
• To specify a default value, add "Default [value]" after the data type declaration.
• In the above example, if we want to default column "Address" to "Unknown" and City to "Karachi", we would type:

CREATE TABLE customer (First_Name char(50), Last_Name char(50), Address char(50) default 'Unknown', City char(50) default 'Mumbai', Country char(25), Birth_Date date);

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