Primary Key « Key « SQL / MySQL

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.A primary key on a column can be created by replacing PRIMARY KEY with UNIQUE in the table definition, provide
15.Add PRIMARY KEY or UNIQUE directly to the end of the column definition.
16.Create a primary key on the last_name and first_name columns using a PRIMARY KEY clause
17.Create a multiple-column primary key using UNIQUE, if the columns are declared NOT NULL
18.Using three column as the primary key
19.Drop primary key