Αποτελέσματα Αναζήτησης
This tutorial shows you how to use Oracle PRIMARY KEY constraint to create, add, disable, enable, and drop a primary key of a table.
13 Ιουλ 2012 · ALTER TABLE table_name ADD CONSTRAINT pk_table_name PRIMARY KEY( new_pk_column ) If you want to generate the key automatically, you'd need to add a trigger. CREATE TRIGGER trigger_name BEFORE INSERT ON table_name FOR EACH ROW BEGIN :new.new_pk_column := sequence_name.nextval; END;
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 TABLE statement in Oracle.
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);
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.
4 Νοε 2020 · Table of Contents. Introduction to Primary Key. How to Add primary key in oracle. Primary Key at Table Creation. Alter Table Add Primary Key. how to create a composite primary key in oracle. how to drop primary key in oracle. How to Enable/Disable Primary Key constraints. How to Add Primary Key using Index.
24 Δεκ 2018 · How to Create a Primary Key Constraint in Oracle Database. Primary key constraint can be defined in two ways: Using CREATE TABLE statement and. Using ALTER TABLE statement. You can define a primary key constraint either during the creation of a table using CREATE TABLE statement or after creating a table using ALTER TABLE statement.
