oracle query all libraries

Oracle database is an enterprise-level database system that supports concurrent access by multiple users. Oracle database has many users, each user has its own database and database tables. Querying all Oracle databases is a common need, especially in large enterprises where there are many Oracle databases that need to be managed and maintained. This article will introduce how to query all Oracle databases and how to perform some common tasks in Oracle databases.

1. Query all Oracle databases

To query all Oracle databases, you need to log in to the Oracle system user first. You can use Oracle client tools such as SQL*Plus or SQL Developer to log in. After successful login, you can execute the following SQL statement to query all Oracle databases:

SELECT NAME FROM V$DATABASE;

After executing the above statement, you can get the names of all Oracle databases. It should be noted here that this statement can only query the Oracle database that has been started. If an Oracle database has not been started, it cannot be queried.

2. Querying the version information of the Oracle database

Querying the version information of the Oracle database is usually an operation required for database upgrade or maintenance. Oracle database version information can be queried through the following SQL statement:

SELECT * FROM V$VERSION;

After executing the above statement, you can get the version information of the currently connected Oracle database, including operating system, Oracle instance, Oracle version and other information.

3. Query the table space information of Oracle database

Table space is the main logical structure for storing data in Oracle database. Querying the table space information of the Oracle database can be queried through the following SQL statement:

SELECT TABLESPACE_NAME, FILE_NAME, BYTES/1024/1024 AS SIZE_MB FROM DBA_DATA_FILES;

After executing the above statement, you can get the names, file names and sizes of all table spaces in the Oracle database.

4. Querying the user information of the Oracle database

Querying the user information of the Oracle database can be queried through the following SQL statement:

SELECT USERNAME, ACCOUNT_STATUS FROM DBA_USERS;

After executing the above statement, You can get the user names and account status of all users in the Oracle database. Account status usually includes LOCKED (locked status), EXPIRED (password expired), OPEN (enabled status), etc.

5. Querying the table information of the Oracle database

Querying the table information of the Oracle database is a common operation for data analysis and monitoring. You can use the following SQL statement to query the information of all tables in the Oracle database:

SELECT TABLE_NAME, NUM_ROWS, LAST_ANALYZED FROM USER_TABLES;

After executing the above statement, you can get the name, number of rows, and last analysis time of all tables in the Oracle database. This information is very helpful for data analysis and table performance optimization.

Summary

Querying all Oracle databases is one of the basic operations for managing and maintaining Oracle databases. In addition, querying the version information, table space information, user information, table information, etc. of the Oracle database are also common operations for managing and maintaining the Oracle database. When querying an Oracle database, you need to use appropriate SQL statements and tools in order to obtain accurate and useful information. Therefore, it is very important to be proficient in the methods and techniques of Oracle database management and maintenance.

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