ORA-12991: column is referenced in a multi-column constraint ORA-12991 means that the column you want to drop is bound to some multi-column constraints. You must… Read More »How to Resolve ORA-12991 Error Message
Modify Primary Key Sometimes, developers may design a better primary key to support the uniqueness of a table and they want to replace the current… Read More »How Oracle Alter Primary Key
Drop Primary Key Primary key is sort of a constraint rather than an index, you should treat it as a constraint first so as to… Read More »How Oracle Drop Primary Key
Add Primary Key There're 3 basic ways to create a primary key for a table. 1. System-Generated Name You don't have to provide a name… Read More »How Oracle Add Primary Key
For getting the information of a primary key, we have to join two dictionary views, one is ALL_CONS_COLUMNS, the other is ALL_CONSTRAINTS. And then we… Read More »How Oracle Check Primary Key of a Table