How to open a database in oracle

To query the Oracle tablespace size, follow the following steps: Determine the tablespace name by running the query: SELECT tablespace_name FROM dba_tablespaces; Query the tablespace size by running the query: SELECT sum(bytes) AS total_size, sum(bytes_free) AS available_space, sum(bytes) - sum(bytes_free) AS used_space FROM dba_data_files WHERE tablespace_

There are three ways to view instance names in Oracle: use the "sqlplus" and "select instance_name from v$instance;" commands on the command line. Use the "show instance_name;" command in SQL*Plus. Check environment variables (ORACLE_SID on Linux) through the operating system's Task Manager, Oracle Enterprise Manager, or through the operating system.

Oracle View Encryption allows you to encrypt data in the view, thereby enhancing the security of sensitive information. The steps include: 1) creating the master encryption key (MEk); 2) creating an encrypted view, specifying the view and MEk to be encrypted; 3) authorizing users to access the encrypted view. How encrypted views work: When a user querys for an encrypted view, Oracle uses MEk to decrypt data, ensuring that only authorized users can access readable data.

Uninstall method for Oracle installation failure: Close Oracle service, delete Oracle program files and registry keys, uninstall Oracle environment variables, and restart the computer. If the uninstall fails, you can uninstall manually using the Oracle Universal Uninstall Tool.

The method to solve the Oracle cursor closure problem includes: explicitly closing the cursor using the CLOSE statement. Declare the cursor in the FOR UPDATE clause so that it automatically closes after the scope is ended. Declare the cursor in the USING clause so that it automatically closes when the associated PL/SQL variable is closed. Use exception handling to ensure that the cursor is closed in any exception situation. Use the connection pool to automatically close the cursor. Disable automatic submission and delay cursor closing.

Oracle Invalid numeric errors may be caused by data type mismatch, numeric overflow, data conversion errors, or data corruption. Troubleshooting steps include checking data types, detecting digital overflows, checking data conversions, checking data corruption, and exploring other possible solutions such as configuring the NLS_NUMERIC_CHARACTERS parameter and enabling data verification logging.

In Oracle, the FOR LOOP loop can create cursors dynamically. The steps are: 1. Define the cursor type; 2. Create the loop; 3. Create the cursor dynamically; 4. Execute the cursor; 5. Close the cursor. Example: A cursor can be created cycle-by-circuit to display the names and salaries of the top 10 employees.

To create a user in Oracle, follow these steps: Create a new user using the CREATE USER statement. Grant the necessary permissions using the GRANT statement. Optional: Use the RESOURCE statement to set the quota. Configure other options such as default roles and temporary tablespaces.