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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_n...
See below the updated sql to retrieve the tables that have a foreign key reference to EMPLOYEES. TABLES.foreign_key => EMPLOYEES.primary_key
Add a foreign key constraint to a table. If you want to add a foreign key constraint to an existing table, you use the ALTER TABLE statement as follows: ALTER TABLE child_table ADD CONSTRAINT fk_name FOREIGN KEY (col1,col2) REFERENCES parent_table(col1,col2); Code language: SQL (Structured Query Language) (sql) Drop a foreign key constraint
A foreign key is a way to enforce referential integrity within your Oracle database. A foreign key means that values in one table must also appear in another table. The referenced table is called the parent table while the table with the foreign key is called the child table.
23 maj 2017 · I'm looking for a query allowing to retrieve foreign key infos (each line: referrencing table & field, referrenced table & field) of an entire schema. I'm currently working on it and may end up with a solution in the next minutes/hours.
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.
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) );
