Correcting an error in a stored procedure

Employer
[no-member:pro]Petr[/no-member:pro]
Project parameters
Type of cooperationOne-time project
SectionWeb development
Prepaymentwithout prepayment
Payment methodsCash, Bank transfer
Acceptance of requestsfrom Feb 27, 2019 until Feb 28, 2019
Project description
Correct the stored procedure
Error of inserting a unique index in the script
Error of inserting a unique index in the script