How to query when the oracle database has been modified

Oracle database provides the following methods to query the table modification time: LAST_CHANGE pseudo column: Returns the last modified timestamp of any record in the table. USER_TAB_MODIFICATIONS view: Stores information about table structure changes, including last modification time. AUDIT TABLE command: Enables or disables table change auditing and records operation timestamps. FLASHBACK QUERY: Allows you to view data at a specific point in time of the table, but the flashback function needs to be enabled.

How to query the modification time of a table in Oracle database

Oracle database provides a variety of methods to query tables The last modification time of the record or table in .

1. Use the LAST_CHANGE

LAST_CHANGE pseudo column to return the last modified timestamp of any row or column in the table.

<code class="sql">SELECT LAST_CHANGE FROM table_name;</code>

2. Use the USER_TAB_MODIFICATIONS view

USER_TAB_MODIFICATIONS The view stores information about table structure changes, including column modifications, adding or deleting indexes, etc. .

<code class="sql">SELECT LAST_DDL_TIME FROM USER_TAB_MODIFICATIONS
WHERE TABLE_NAME = 'table_name';</code>

3. Use the AUDIT TABLE command

AUDIT TABLE command to enable or disable auditing of table changes. When enabled, the database will log all DML operations (inserts, updates, and deletes), including the timestamp of the operations.

To enable auditing:

<code class="sql">AUDIT TABLE table_name;</code>

To query the audit trail:

<code class="sql">SELECT TIMESTAMP, OPERATION, USERNAME
FROM AUDIT_TRAIL
WHERE TABLE_NAME = 'table_name';</code>

4. Use FLASHBACK QUERY

FLASHBACK The QUERY function allows you to view data for a table or view at a specific point in time. This can be used to view the modification history of a table.

<code class="sql">SELECT * FROM table_name AS OF TIMESTAMP AS_OF_TIMESTAMP;</code>

Note:

• For the LAST_CHANGE pseudo column, meaningful values ​​are returned only if there are modified rows in the table .
• USER_TAB_MODIFICATIONS The view will only log structural changes, not data changes.
• AUDIT TABLE The command requires administrator privileges.
• FLASHBACK QUERY Requires flashback function to be enabled and sufficient flashback area.

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