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This tutorial shows you how to use Oracle PRIMARY KEY constraint to create, add, disable, enable, and drop a primary key of a table.
You can create a primary key in Oracle with the ALTER TABLE statement. Syntax. The syntax to create a primary key using the ALTER TABLE statement in Oracle/PLSQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1, column2, ... column_n); Example. Let's look at an example of how to create a primary key using the ALTER ...
To create a PRIMARY KEY constraint on the "ID" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Persons. ADD PRIMARY KEY (ID);
13 Ιουλ 2012 · SET new_pk_column = sequence_name.nextval; Once that's done, you can create the primary key constraint (this assumes that either there is no existing primary key constraint or that you have already dropped the existing primary key constraint) ALTER TABLE table_name.
Primary Key Example. The following statement is a variation of the statement that created the sample table hr.locations. It creates the locations_demo table and defines and enables a primary key on the location_id column (other constraints from the hr.locations table are omitted):
Oracle PRIMARY KEY Constraint with Examples. In this article, we will be learning about the Primary constraints and how to create, alter, drop or enable/disable them in Oracle. What is a Primary Key? The Primary Key constraint is used for uniquely identifying each row of a table.
5 Σεπ 2019 · To add a primary key constraint to an existing table using ALTER TABLE statement, here is the generic syntax: ALTER TABLE table_name ADD CONSTRAINT constraint_name PRIMARY KEY (column1, column2, ... column_n);
