Useful Tips

How can I find out what foreign key constraint references a table in Oracle?

How can I find out what foreign key constraint references a table in Oracle?

First method is with table Constraints tab (select table and select Constraints tab). Tab lists table constraints – primary, unique and foreign keys and check constraints – all in one grid. Foreign keys are the ones with ‘Foreign_Key’ value in CONSTRAINT_TYPE column. R_TABLE_NAME holds primary table name.

How do you identify all foreign key references in a table?

The most Simplest one is by using sys. foreign_keys_columns in SQL. Here the table contains the Object ids of all the foreign keys wrt their Referenced column ID Referenced Table ID as well as the Referencing Columns and Tables.

How can I find all foreign key references to a table in SQL Server?

List All Foreign Keys Referencing A Table In SQL Server

  1. Using sp_fkey. One among the easiest way to list all foreign key referencing a table is to use the system stored procedure sp_fkey.
  2. Using sp_help.
  3. Using SSMS GUI.
  4. Using sys.
  5. Reference.

Can we have two foreign keys in a table in Oracle?

You can use the FOREIGN KEY REFERENCES constraint to implement a foreign key relationship in SQL Server. Specify the table name. Then specify in parenthesis the column name for the foreign key to reference it.

How do you insert a table in foreign key?

If you are inserting data into a dependent table with foreign keys:

  1. Each non-null value you insert into a foreign key column must be equal to some value in the corresponding parent key of the parent table.
  2. If any column in the foreign key is null, the entire foreign key is considered null.

How many foreign keys can be there in a table?

253 foreign key references
A table with a foreign key reference to itself is still limited to 253 foreign key references. Greater than 253 foreign key references are not currently available for columnstore indexes, memory-optimized tables, Stretch Database, or partitioned foreign key tables.

Can a foreign key reference a non primary key?

A foreign key can refer to either a unique or a primary key of the parent table. If the foreign key refers to a non-primary unique key, you must specify the column names of the key explicitly.