Can a foreign key have the same name as a primary key?

To facilitate keeping key variable names consistent, and to provide for programs that do natural joins, foreign keys have the same name as is used in the table in which they are the primary key.

Can a table have the same primary and foreign key?

Yes, it is legal to have a primary key being a foreign key. This is a rare construct, but it applies for: a 1:1 relation. The two tables cannot be merged in one because of different permissions and privileges only apply at table level (as of 2017, such a database would be odd).

Does foreign key should have the same name?

Yes it is ok. Read sqlite foreign key document. It gives similar example. As you can see, column names are not same, but foreign key added nonetheless.

Does a foreign key have to match a primary key?

The data type of the foreign key does not match that of the primary key. But it also prevents a database from declaring referential integrity to keep a foreign key consistent with its referent.

Can a table have two primary keys?

A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

What do you understand by a foreign key show the relation between a primary and foreign key with a suitable example?

A primary key is used to ensure data in the specific column is unique. A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables. It uniquely identifies a record in the relational database table. Whereas more than one foreign key are allowed in a table.

What is another name for primary key?

A primary key, also called a primary keyword, is a key in a relational database that is unique for each record. It is a unique identifier, such as a driver license number, telephone number (including area code), or vehicle identification number (VIN).

Can you truncate the table whose primary key is lined as foreign key in another table?

Cannot truncate table because it is being referenced by a FOREIGN KEY constraint.

Can a foreign key reference its own table?

If you mean “can foreign key ‘refer’ to a primary key in the same table?”, the answer is a firm yes as some replied.

What happens to the data of the table with the foreign key when the table with primary have there data updated?

No the foreign key is not updated automatically. You need to update the foreign key in the tables in which it is referenced by yourself else it would result in referential integrity exception. For updating the foreign key automatically you may use TRIGGERS.

Does a table have to have a primary key?

Every table can have (but does not have to have) a primary key. The column or columns defined as the primary key ensure uniqueness in the table; no two rows can have the same key. The primary key of one table may also help to identify records in other tables, and be part of the second table’s primary key.

How do you define a foreign key in PostgreSQL?

In PostgreSQL, you define a foreign key through a foreign key constraint. A foreign key constraint indicates that values in a column or a group of columns in the child table match with the values in a column or a group of columns of the parent table.

How do you add a foreign key to a table?

In this syntax: 1 First, specify the name for the foreign key constraint after the CONSTRAINT keyword. 2 Second, specify one or more foreign key columns in parentheses after the FOREIGN KEY keywords. 3 Third, specify the parent table and parent key columns referenced by the foreign key columns in the REFERENCES clause.

Can a column be a primary key and foreign key?

If you mean “can column (or set of columns) be a primary key as well as a foreign key in the same table?”, the answer, in my view, is a no; it seems meaningless. However, the following definition succeeds in SQL Server! But I think it is meaningless to have such a constraint unless somebody comes up with a practical example.

What is the use of foreign key constraint in SQL?

The foreign key constraint helps maintain the referential integrity of data between the child and parent tables. A foreign key constraint indicates that values in a column or a group of columns in the child table equal the values in a column or a group of columns of the parent table.