why when creating table i must use ` and not '

pelegk2

why when creating a table :

PHP Code:
CREATE TABLE guestbook ( user_id MEDIUMINT( 5 ) NOT NULL AUTO_INCREMENT , user_name VARCHAR( 40 ) NOT NULL , user_email VARCHAR( 40 ) NOT NULL , user_message TEXT NOT NULL , msg_time VARCHAR( 30 ) NOT NULL , PRIMARY KEY ( user_id ) )

so why when creating table i must use ` and not '?

eoghain

Your question doesn't makes sence the way it's worded, but I'm assuming that you are wonding why you have to put NOT NULL as a part of your column definitions. The short answer is you don't. Adding NOT NULL tells the database that you don't ever want that column to contain null values, that means that the column always has to have data.

Lets look at a typical (US) address table:
Address1 varchar(50) NOT NULL
Address2 varchar(5)
City varchar(50) NOT NULL
State varchar(50) NOT NULL
Zip char(5) NOT NULL

As you can see there are the standard 5 columns all of the columns except for Address2 are set as NOT NULL meaning that they have to be populated with data for the record to be allowed to be inserted. But Address2 isn't set as NOT NULL because many addresses don't have a line 2. So both of the below addresses would be allowed to be inserted into the database:

123 Main St.

AnyCity
AnyState
12345

-and-

123 Main St.
Suite A
AnyCity
AnyState
12345

However if you tried to leave out the Address1, City, State, or Zip field then the record wouldn't be allowed to be entered because those fields can't be null.

pelegk2

m question was :

why when creating table i must use

`QUOTE]
and not

'

when i create a table by code!

nemonoman

...and what we are replying is:

We looked at your code and don't see
'and not' anywhere in it.

bastien

mysql ( and the sql langauge) interpret the backtick (`) differently than the single quote (').

Single quotes are used to define text elements in a sql strin

ie
sql= "select * from tablename where name like '$name'";

the back ticks are used to encapsulate the table/field names especially if you have charcaters which are frowned upon in the general scheme of things, like spaces or other diallowed characters in the table/fieldnames

hth