Cannot create new user due to primary key violation or unique constraint error

Here are the exceptions from various databases:

Oracle:

org.springframework.dao.DataIntegrityViolationException: (Hibernate operation): data integrity violated by SQL ''; nested exception is java.sql.BatchUpdateException: ORA-00001: unique constraint (CWK.SYS_C002106) violated
at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.translate(SQLStateSQLExceptionTranslator.java:88)
caused by: java.sql.BatchUpdateException: ORA-00001: unique constraint (CWK.SYS_C002106) violated
at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:367)

MS SQL Server:

org.springframework.dao.DataIntegrityViolationException: (Hibernate operation): data integrity violated by SQL ''; nested exception is java.sql.SQLException: Violation of PRIMARY KEY constraint 'PK_os_user_5070F446'. Cannot insert duplicate key in object 'os_user'.
at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.translate(SQLStateSQLExceptionTranslator.java:88)
caused by: java.sql.SQLException: Violation of PRIMARY KEY constraint 'PK_os_user_5070F446'. Cannot insert duplicate key in object 'os_user'.
at net.sourceforge.jtds.jdbc.SQLDiagnostic.addDiagnostic(SQLDiagnostic.java:365)

MySQL:

org.springframework.dao.DataIntegrityViolationException: (Hibernate operation): data integrity violated by SQL ''; nested exception is java.sql.BatchUpdateException: Duplicate entry '1' for key 1
at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.translate(SQLStateSQLExceptionTranslator.java:88)
caused by: java.sql.BatchUpdateException: Duplicate entry '1' for key 1
at com.mysql.jdbc.ServerPreparedStatement.executeBatch(ServerPreparedStatement.java:647)