The DBA_, ALL_, and USER_ views in Oracle database represent data dictionary perspectives at different permission levels. 1. The USER_view displays objects owned by the user, such as USER_TABLES and USER_CONSTRAINTS, which are suitable for developers or ordinary users to view their own objects; 2. The ALL_view contains all objects that the user has access rights, whether owned or not, such as ALL_TABLES and ALL_VIEWS, which are suitable for confirming accessible data in shared mode; 3. The DBA_view displays all objects in the database, but is only accessible to DBA or users with advanced permissions, such as DBA_USERS and DBA_TABLES, which are often used for system-level management and troubleshooting. The selection basis is: the application user uses USER_, check ALL_ when accessing shared data, and use DBA_ when managing the overall system.

In Oracle databases, the DBA_ , ALL_ , and USER_ views are key components of the data dictionary. They provide different perspectives on database metadata depending on what kind of access and visibility you need.

What Do These Prefixes Mean?

• USER_ views show information about objects you own .
• ALL_ views include objects that you have access to — either because you own them or because you've been granted privileges on them.
• DBA_ views show everything in the database — but only if you have DBA-level privileges (or equivalent).

So, if you're a regular user, you'll probably use USER_ and maybe ALL_ . If you're a DBA, you'll lean more on DBA_ .

When to Use USER_ Views

Use these when you want to see only the objects you own.

For example:

• USER_TABLES shows all tables you own.
• USER_CONSTRAINTS shows constraints you've defined.

This is useful for developers or end users who don't need to know about other people's objects.

? Tip: If you're debugging your own schema or checking your own table structures, start with USER_ views. They help avoid distractions from irrelevant data.

Why ALL_ Views Matter

These views show all objects you can access — whether you own them or not.

Examples:

• ALL_TABLES includes tables owned by others that you can query.
• ALL_VIEWS shows all views available to you.

This is helpful when you're working with shared schemas or trying to understand what data you can actually access.

? Common scenario: You're writing a query and wonder, “Can I access this table?” Check ALL_TABLES to confirm it exists and is accessible.

What Makes DBA_ Views Special

Only accessible to DBAs or users with elevated privileges.

They include:

• DBA_USERS : All users in the system.
• DBA_TABLES : Every table in the database.
• DBA_OBJECTS : Every object across all schemas.

? Important note: Accessing these require special permissions like the SELECT ANY DICTIONARY privilege or being part of the DBA role.

?? Typical use case: When diagnosed performance issues, managing space, or auditing security settings across the entire database.

Choosing the Right View

Here's how to decide which one to use:

• If you're a developer or application user → start with USER_
• If you're accessing shared data → check ALL_
• If you're managing or troubleshooting the whole system → go with DBA_

Also remember:

• Not all views exist in all three forms — some are only available as ALL_ or USER_ .
• The structure of these views is similar, so once you learn one, the others are easy to follow.

Basically, these prefixes help control what level of detail you see in the data dictionary — from narrow ( USER_ ) to full ( DBA_ ). Knowing which one to use saves time and avoids unnecessary complexity.

The above is the detailed content of What is the role of the DBA_ , ALL_ , and USER_ data dictionary views?. For more information, please follow other related articles on the PHP Chinese website!