I have made a table which is as follows (CREATE TABLE Dept (Dcode number(2) primary key, Dname varchar2(20) unique check (Dname in (‘Acc’, ‘Resea’, ‘Ope’, ‘Exe’)), Floor varchar2(2)Not null);)

Insert command (INSERT INTO Dept VALUES (13,’Exe’,’G’);)

When I am trying to enter data in it it shows the following message
**Error starting at line : 21 in command –
INSERT INTO Dept VALUES (13,’Exe’,’G’)
Error report –
ORA-00001: unique constraint (WAJID.SYS_C007019) violated
**
what should I do?

I have tried to database table in sql developer but it showing error.
help me!!