Thread: Different data type for primary and foreign keys

Is it possible that Primary key and foreign keys hav diff. data type?
if No then is below eg valid...what length of deptid is diff in both the tableseg.emp table having (empid varchar2(10),deptid varchar2(25)) --deptid is foreign key dept table having (deptid varchar2(10),deptname varchar2(20) --deptid is primary key

Question asked by visitor sant

Varchar2 data type does pad values with blank spaces. If number of digits is same then it does not matter.

Yes of course they can have different data types in a table.

But the foreign key and the PK or unique key of the referenced table should have same datatype.

The nth FOREIGN KEY column corresponds to the nth column in the primary key of the REFERENCES table, and the data types and lengths of corresponding columns must be identical. Columns may not be used more than once in the same FOREIGN KEY clause.

Example
create table customer(
id varchar2(6) primary key,
NAME VARCHAR2(15 BYTE))

create table account (
id varchar2(5) references customer(id),
type VARCHAR2(20 BYTE)
)

While inserting id(same as custormer(id)) into account we will get an error