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?

You can check for foreign key constraint errors by looking at the dba_constraints and the dba_cons_columns views. Using the cascade constraints clause in a drop table will force a cascade delete to occur in all child tables. Oracle also has the drop table if exists feature.

Can a foreign key reference its own table?

FOREIGN KEY constraints can reference another column in the same table, and is referred to as a self-reference. A FOREIGN KEY constraint specified at the column level can list only one reference column. This column must have the same data type as the column on which the constraint is defined.

How can I find which tables reference a given table in Oracle?

1 Answer

  1. select table_name, constraint_name, status, owner.
  2. from all_constraints.
  3. where r_owner = :r_owner.
  4. and constraint_type = ‘R’
  5. and r_constraint_name in.
  6. select constraint_name from all_constraints.
  7. where constraint_type in (‘P’, ‘U’)
  8. and table_name = :r_table_name.

What could the foreign key of a table reference?

A Foreign Key is a database key that is used to link two tables together. The FOREIGN KEY constraint identifies the relationships between the database tables by referencing a column, or set of columns, in the Child table that contains the foreign key, to the PRIMARY KEY column or set of columns, in the Parent table.

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 multiple tables?

A field that acts as a foreign key can do so in more than one relationships to different tables. So although a foreign key is unique you can have (and it’s not uncommon to have) multiple foreign keys that use the same field to link a parent to multiple children tables in a one-to-many relationship.

Can foreign key have different name?

A foreign key can also have different column names than the primary key. The foreign key and primary key can also have different default values. Default values are also not used very often for foreign key columns. Although primary key values must be unique, foreign key values are not required to be unique.

Where is foreign key reference in Oracle SQL Developer?

Foreign keys in Constraints tab 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.

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

Using SQL Server Management Studio

  1. Open the Table Designer for the table containing the foreign key you want to view, right-click in the Table Designer, and choose Relationships from the shortcut menu.
  2. In the Foreign Key Relationships dialog box, select the relationship with properties you want to view.

Can a foreign key reference a non primary key?

Yes, a foreign key can reference a non-primary key which is unique. A FOREIGN KEY constraint does not have to be linked only to a PRIMARY KEY constraint in another table; it can also be defined to reference the columns of a UNIQUE constraint in another table.

Can a foreign key reference a foreign key?

A foreign key can reference any field defined as unique. If that unique field is itself defined as a foreign key, it makes no difference. If it is a unique field, it can also be the target of another FK.