Create Foreign key in Sql
How To create Foreign key in sql table :
You have a code(for table)like this:
create table person( name varchar2(5),
Id_no number(3),
Address number(10) );
and you have another table of place:
create table place(name varchar2(5)primary key,
location varchar2(5),
owner_name varchar2(5) );
Column Order:
create table place(name varchar2(5) primary key,
location varchar2(5),
owner_name varchar2(5) references person(name) );
==================================================
Table Order:
create table place(name varchar2(5) primary key,
location varchar2(5),
owner_name varchar2(5),
constraint n_pk foreign key (owner_name) references person(name) );
Note:All the bold words are reserved word in Sql.
You have a code(for table)like this:
create table person( name varchar2(5),
Id_no number(3),
Address number(10) );
and you have another table of place:
create table place(name varchar2(5)primary key,
location varchar2(5),
owner_name varchar2(5) );
Now you want to make owner_name as Foreign key which relate name of person to the owner name of place table. so there are two methods to make a column foreign key one in table order and other one is column order.
===================================================Column Order:
create table place(name varchar2(5) primary key,
location varchar2(5),
owner_name varchar2(5) references person(name) );
==================================================
Table Order:
create table place(name varchar2(5) primary key,
location varchar2(5),
owner_name varchar2(5),
constraint n_pk foreign key (owner_name) references person(name) );
Note:All the bold words are reserved word in Sql.
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