Sybase 12.4.2 ユーザーズマニュアル

CHAPTER 3    Working with Database Objects

The

 CREATE TABLE 

and 

ALTER TABLE 

statements allow many attributes of 

tables to be set, including column constraints and checks. This section shows 
how to set table attributes using the primary and foreign keys as an example.

Creating a primary 
key

The following statement creates the same 

skill

 table as before, except that a 

primary key is added:

CREATE TABLE skill (

  skill_id INTEGER NOT NULL,

  skill_name CHAR( 20 ) NOT NULL,

  skill_type CHAR( 20 ) NOT NULL,

  primary key( skill_id )

)

The primary key values must be unique for each row in the table which, in this 
case, means that you cannot have more than one row with a given 

skill_id

. Each 

row in a table is uniquely identified by its primary key.

Columns in the primary key are not allowed to contain NULL. You must 
specify 

NOT NULL

 on the column in the primary key.

Adaptive Server IQ does not enforce multi-column primary keys. You 

must specify the keyword 

UNENFORCED

 when you define a multi-column 

primary key.

Creating a primary 
key in Sybase Central

❖

1

Connect to the database.

2

Click the Tables folder for that database.

3

Right-click the table you wish to modify, and select Properties from the 
pop-up menu to display its property sheet.

4

Click the Columns tab, select the column name, and either click Add to 
Key or Remove from Key.