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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,...)
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);
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
Foreign key constraints use the references_clause syntax. When you specify a foreign key constraint inline, you need only the references_clause. When you specify a foreign key constraint out of line, you must also specify the FOREIGNKEY keywords and one or more columns. ON DELETE Clause.
10 wrz 2024 · In PL/SQL, a foreign key creates relationships between tables, ensuring that the data in one table corresponds to the data in another. This article will explore the concept of foreign keys in Oracle PL/SQL, provide examples using the CREATE TABLE and ALTER TABLE statements, and explain their syntax, output, What is a Foreign Key in Oracle?
19 mar 2019 · I'm trying to find a query which will return me a list of the foreign keys for a table and the tables and columns they reference. I am half way there with SELECT a.table_name, a.column_name, a.constraint_name, c.owner FROM ALL_CONS_COLUMNS A, ALL_CONSTRAINTS C where A.CONSTRAINT_NAME = C.CONSTRAINT_NAME and a.table_name=:TableName and C ...
The syntax to add a Foreign Key constraint using CREATE TABLE Statement is as follows: Syntax. CREATE TABLE table_name ( column1 datatype, column2 datatype, ... CONSTRAINT fk_column FOREIGN KEY (column1, column2, ... column_n) REFERENCES parent_table (column1, column2, ... column_n) );
