How to view primary key constraints in Oracle?

In Oracle database, you can view primary key constraints using the following method:

1. With the DESCRIBE command, you can view the structure of a table, including any primary key constraints. For example, if you have a table named “employees”, you can use the command DESCRIBE employees to see its structure. The primary key constraint will be displayed in the “Key” column in the results.
2. Using the SELECT statement to query constraint information: You can use the following query to view information about primary key constraints:
   SELECT constraint_name, constraint_type, table_name
   FROM user_constraints
   WHERE constraint_type = ‘P’
   AND table_name = ’employees’;
   This will return a result set that includes information about the primary key constraint for a table named “employees”.
3. You can query system views to retrieve constraint information. For example, you can use the following query to view all primary key constraints for the current user:
   SELECT constraint_name, table_name
   FROM user_constraints
   WHERE constraint_type = ‘P’;
   This will return a result set containing all primary key constraints for the current user.

Please note that these methods all require sufficient privileges to view constraint information. If you are unable to perform the above methods, please contact the database administrator or a user with sufficient privileges to view primary key constraints.