Friday, 5 September 2014

SQL

The SQL CREATE DATABASE Statement

The CREATE DATABASE statement is used to create a database.

SQL CREATE DATABASE Syntax

CREATE DATABASE dbname;


SQL CREATE DATABASE Example

The following SQL statement creates a database called "my_db":
CREATE DATABASE my_db;
Database tables can be added with the CREATE TABLE statement.


The SQL CREATE TABLE Statement

The CREATE TABLE statement is used to create a table in a database.
Tables are organized into rows and columns; and each table must have a name.

SQL CREATE TABLE Syntax

CREATE TABLE table_name
(
column_name1 data_type(size),
column_name2 data_type(size),
column_name3 data_type(size),
....
);
The column_name parameters specify the names of the columns of the table.
The data_type parameter specifies what type of data the column can hold (e.g. varchar, integer, decimal, date, etc.).
The size parameter specifies the maximum length of the column of the table.



SQL CREATE TABLE Example

Now we want to create a table called "Persons" that contains five columns: PersonID, LastName, FirstName, Address, and City.
We use the following CREATE TABLE statement:

Example

CREATE TABLE Persons
(
PersonID int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);

The PersonID column is of type int and will hold an integer.

The LastName, FirstName, Address, and City columns are of type varchar and will hold characters, and the maximum length for these fields is 255 characters.
The empty "Persons" table will now look like this:
PersonID       LastName      FirstName     Address      City
     
Tip: The empty table can be filled with data with the INSERT INTO statement.

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