A primary key on a column can be created by replacing PRIMARY KEY with UNIQUE in the table definition, provide : Primary Key « Key « SQL / MySQL






  1. SQL / MySQL
  2. Key
  3. Primary Key

A primary key on a column can be created by replacing PRIMARY KEY with UNIQUE in the table definition, provide

     
d that the column is declared NOT NULL:
mysql>
mysql> CREATE TABLE t
    -> (
    ->     id   INT NOT NULL,
    ->     name CHAR(30) NOT NULL,
    ->     UNIQUE (id)
    -> );
Query OK, 0 rows affected (0.00 sec)








Related examples in the same category

1.Setting a Primary Key 1
2.Setting a Primary Key 2
3.Setting a Primary Key 3
4.Define and use primary key
5.Alter table to Add an PRIMARY KEY
6.Another way to enforce uniqueness is to add a UNIQUE index rather than a PRIMARY KEY to a table.
7.To drop an index that is not a PRIMARY KEY, you must specify the index name.
8.Adding primary key for not null column
9.Defining Primary Keys
10.Use a PRIMARY KEY constraint
11.If you were creating a primary key on more than one column, you would include both of those column names in th
12.Two ways to declare primary key when creating the table
13.Create a table t that contains an id column that's NOT NULL and declared as a primary key by means of a PRIMAR
14.Add PRIMARY KEY or UNIQUE directly to the end of the column definition.
15.Create a primary key on the last_name and first_name columns using a PRIMARY KEY clause
16.Create a multiple-column primary key using UNIQUE, if the columns are declared NOT NULL
17.Using three column as the primary key
18.Drop primary key