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Oracle foreign key constraint syntax. Oracle allows you to create, add, drop, disable, and enable a foreign key constraint. Create a foreign key constraint. The following statement illustrates the syntax of creating a foreign key constraint when you create a table: CREATE TABLE child_table ( ... CONSTRAINT fk_name FOREIGN KEY (col1, col2,...)
To allow naming of a FOREIGN KEY constraint, and for defining a FOREIGN KEY constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Orders. ADD CONSTRAINT FK_PersonOrder.
Syntax. The syntax for creating a foreign key in an ALTER TABLE statement is: ALTER TABLE table_name ADD CONSTRAINT constraint_name FOREIGN KEY (column1, column2, ... column_n) REFERENCES parent_table (column1, column2, ... column_n); Example
A foreign key constraint (also called a referential integrity constraint) designates a column as the foreign key and establishes a relationship between that foreign key and a specified primary or unique key, called the referenced key.
To allow naming of a FOREIGN KEY constraint, and for defining a FOREIGN KEY constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Orders
15 lip 2013 · Microsoft SQL Server syntax: ALTER TABLE one. ADD two_id INTEGER, FOREIGN KEY(two_id) REFERENCES two(id);
This tutorial helps you understand SQL foreign key and show you how to define a foreign key using the FOREIGN KEY constraints.
