We can use the DEFAULT keyword to specify a default value for a column.

CREATE TABLE Users
(
    UserID int NOT NULL,
    FirstName varchar(100) NOT NULL,
    LastName varchar(100) NOT NULL,
    Email varchar(200),
    Phone varchar(50),
    City varchar(50) DEFAULT 'Toronto',
    CreatedDate Date DEFAULT Getdate()
)

The above script will create a table named “Users”, the default value of column “City” will be “Toronto” and the default value of column “CreatedDate” will be the date when the new row inserted.

When we execute the following script:

INSERT INTO Users(UserID, FirstName, LastName, Email, Phone)
VALUES (1, 'Tom', 'Smith', 'tom.smith@sql-statements.com', '1-000-0000')

We didn’t specify the value for the cloumn City and CreatedDate, so the default value will be set for them:

CREATE TABLE Users
(
    UserID int NOT NULL,
    FirstName varchar(100) NOT NULL,
    LastName varchar(100) NOT NULL,
    Email varchar(200),
    Phone varchar(50),
    Birthday Date
)

The above script will create a table named “Users”, the column UserID, FirstName and LastName cannot hold NULL value. If you try to insert a row without specify the UserID, FirstName or LastName:

INSERT INTO Users (UserID, FirstName, Email, Phone, Birthday)
VALUES (1, 'Tom', 'test@test.com', '999-9999', '1992-12-12')

You would get an error, because the LastName is not specified and would be set a NULL value.

SQL CREATE TABLE Syntax

CREATE TABLE table_name
(
    column1 data_type [null/not null],
    column2 data_type [null/not null],
    column3 data_type [null/not null],
    ....
)

data_type is required.
null/not null is optional, if it is not specified, the default value is null.

SQL CREATE TABLE Example

We want to create a table Users which will store the user’s information: user’s ID, first name, last name, E-mail address, phone number, birthday.

We can use the following script to create a table “Users” in database:

CREATE TABLE Users
(
    UserID int NOT NULL,
    FirstName varchar(100) NOT NULL,
    LastName varchar(100) NOT NULL,
    Email varchar(200),
    Phone varchar(50),
    Birthday Date
)

The script will create an empty table which has 6 columns: UserID, FirstName, LastName, Email, Phone and Birthday.
The UserID, FirstName, LastName will not accept NULL value, when we insert or update a row in database, we must set the values for them. Email, Phone and Birthday can accept NULL value.

The new created empty table will look like:

ORACLE TO_CHAR Function Syntax

The Oracle to_date() function’s syntax could be one of the following:

to_char(value)

to_char(value, format)

to_char(value, format, nls_language)

value: number or date, which will be converted to string.
format: the format we will use to convert a number or date to string.

The format mask parameters for date expression are listed as following: (They could be used in combinations)

ORACLE TO_CHAR Function Example

Numbers Example

SELECT to_char(18.34) FROM dual
-- return a string value: 18.34

SELECT to_char(18.34, '99.9') FROM dual
-- return a string value: 18.3

SELECT to_char(2118.34, '9,999.9') FROM dual
-- return a string value: 2,118.3

SELECT to_char(118, '0009') FROM dual
-- return a string value: 0118

Dates Example

SELECT to_char(sysdate) FROM dual
-- return a string value: 14-DEC-11

SELECT to_char(sysdate, 'mm/dd/yyyy') FROM dual
-- return a string value: 12/14/2011

SELECT to_char(sysdate, 'Mon mm, yy') FROM dual
-- return a string value: Dec 12, 11

SELECT to_char(sysdate, 'Mon mm, yyyy hh:mi am') FROM dual
-- return a string value: Dec 12, 2011 02:48 AM

SQL REVERSE function Syntax

REVERSE(string-expression)

SQL REVERSE function Example

SELECT REVERSE('SQL Tutorial')
-- The result will be: lairotuT LQS

SELECT REVERSE('Monday')
-- The result will be: yadnoM

For example, if we set the length to 10: char(10), varchar(10), and we set the value to ‘apple’:
The stored data for Char(10) is: ‘apple     ’.
The stored data for Varchar(10) is: ‘apple’.

Char and Varchar cannot store Unicode characters.
‘n’ means it can store Unicode characters such as: nchar and nvarchar.

You can have a quick reference:

SQL LEFT Function Syntax

LEFT(str, len)

Note:
1, If str is NULL, the return value will be NULL.
2. If len is greater than the length of str, the return value will be the entire str.
3. If len is 0, the return value will be empty string.

SQL LEFT Function Example

SELECT LEFT('SQL Tutorial',3)
-- The return value will be: SQL

SELECT LEFT('SQL Tutorial',0)
-- The return value will be: Empty string

SELECT LEFT(NULL,3)
-- The return value will be NULL

SELECT LEFT('David',20)
-- The return value will be: David

SQL SPACE Function Syntax

SPACE(int)

int: the number of the spaces.

SQL SPACE Function Example

SELECT SPACE(9)
-- Will return 9 space characters.

SELECT 'Hello' + SPACE(3) + 'World!'
-- Will return 'Hello   World!'
-- 'Hello', then 3 spaces, then 'World!'

SELECT 'Hello' + SPACE(0) + 'World!'
-- Will return 'HelloWorld!'
-- 'Hello', no space, then 'World!'

SQL CHAR Function Syntax

CHAR (int)

SQL CHAR Function Example

SELECT CHAR(83) -- Return: S

SELECT CHAR(81) -- Return: Q

SELECT CHAR(76) -- Return: L

SELECT CHAR(45) -- Return: -

SELECT CHAR(100) -- Return: d

Who Needs SQL Hosting

Basically, if you want to store and retrieve data from SQL databases, you need SQL hosting.

It has some advantages by using SQL hosting:

• Your web application will be robust and scalable.
• Your web page content will be more searchable in database.
• It’ll be easier to maintain the web page content.
• You can easily change the web application’s layout without touching the data.
• You can easily use the same data all through your applications.

SQL Hosting Comparison

It has different SQL databases in the hosting market, you may need to choose one according to your requirements. Following is the basic comparison for your quick reference.