Question

Create a table in SQL with foreign key reference:

1.Create the three tables without any columns

2.Alter the tables to add the columns

3.Alter the tables to create the primary and foreign keys

Answer 1

SQL statements-->

1->

create 3 empty tables ->

CREATE TABLE TABLE1("\0");

CREATE TABLE TABLE2("\0");

CREATE TABLE TABLE3("\0");

These 3 statements will create 3 table with 0 columns and records.

CREATE is used to create

TABLE is used to give table name

TABLE1 is table name

\0 is used to set 0 columns.

2-->

  to add columns to a table -->

ALTER TABLE TABLE1 ADD FirstName varchar(55);

ALTER TABLE Table1 ADD ID integer(5);

ALTER TABLE Table1 ADD orderID integer(5);

now for table 2 -

ALTER TABLE TABLE2 ADD FirstName varchar(55);

ALTER TABLE Table2 ADD ID integer(5);

ALTER TABLE Table2 ADD orderID integer(5);

same for table 3

3 -->

now we add primary and foreign key -->

ALTER TABLE TABLE1 ADD CONSTRAINT PK_Person PRIMARY KEY (ID);

ALTER TABLE TABLE2 ADD CONSTRAINT PK_Person PRIMARY KEY (orderID);

ALTER TABLE TABLE1 ADD FOREIGN KEY (orderID) REFERENCES TABLE2(orderID);

like this we can add primary and foreign keys