About a Table creation,Inserting Data,Data Retrieval

1.CREATE Table :
Creating a basic table involves naming the table and defining its columns and each column's data type.
The SQL CREATE TABLE statement is used to create a new table.

Syntax:
Basic syntax of CREATE TABLE statement is as follows:

CREATE TABLE table_name(
                   column1 datatype,
                   column2 datatype,
                   column3 datatype,
                    .....
                   columnN datatype,
                PRIMARY KEY( one or more columns )
           );

CREATE TABLE is the keyword telling the database system what you want to do. In this case, you want to create a new table. The unique name or identifier for the table follows the CREATE TABLE statement.

Then in brackets comes the list defining each column in the table and what sort of data type it is. The syntax becomes clearer with an example below.

A copy of an existing table can be created using a combination of the CREATE TABLE statement and the SELECT statement. You can check complete details at Create Table Using another Table.

Example:

Following is an example, which creates a CUSTOMERS table with ID as primary key and NOT NULL are the constraints showing that these fields can not be NULL while creating records in this table:

SQL> CREATE TABLE CUSTOMERS(
ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, AGE INT NOT NULL, ADDRESS CHAR (25) , SALARY DECIMAL (18, 2), PRIMARY KEY (ID));

You can verify if your table has been created successfully by looking at the message displayed by the SQL Server , otherwise you can use DESC command as follows..

SQL> DESC CUSTOMERS;

+---------+---------------+------+-----+---------+-------+

| Field   | Type          | Null | Key | Default | Extra |

+---------+---------------+------+-----+---------+-------+

| ID      | int(11)       | NO   | PRI |         |       |

| NAME    | varchar(20)   | NO   |     |         |       |

| AGE     | int(11)       | NO   |     |         |       |

| ADDRESS | char(25)      | YES  |     | NULL    |       |

| SALARY  | decimal(18,2) | YES  |     | NULL    |       |

+---------+---------------+------+-----+---------+-------+

5 rows in set (0.00 sec)


2. INSERT Query
The SQL INSERT INTO Statement is used to add new rows of data to a table in the database.
Syntax:
INSERT INTO TABLE_NAME (column1, column2, column3,...columnN)] 
Here, column1, column2,...columnN are the names of the columns in the table into which you want to insert data.
You may not need to specify the column(s) name in the SQL query if you are adding values for all the columns of the table. But make sure the order of the values is in the same order as the columns in the table. The SQL INSERT INTO syntax would be as follows:
               INSERT INTO TABLE_NAME VALUES (value1,value2,value3,...valueN);



There are two basic syntaxes of INSERT INTO statement as follows:

VALUES (value1, value2, value3,...valueN);





3. SELECT Statement

SQL SELECT statement is used to fetch the data from a database table which returns data in the form of result table. These result tables are called result-sets.

Syntax:

The basic syntax of SELECT statement is as follows:

              SELECT column1, column2, columnN FROM table_name;

Here, column1, column2...are the fields of a table whose values you want to fetch. If you want to fetch all the fields available in the field, then you can use the following syntax:


SELECT * FROM table_name;