Table of contents
Use of the SPOOL command
In Oracle, SPOOL is a SQLPLUS command used to save the output of executing SQL scripts to a specified file. The SPOOL command can help users quickly export query results, generate reports and other common tasks.
1. Basic grammar:
The basic syntax of the SPOOL command is:
SPOOL file_name[.ext] [replace|append]
Among them, `file_name` indicates the file name (including the path) to save the output result, `.ext` can specify the file extension name, the default is `.lis`; `replace|append` is an optional parameter, indicating whether to overwrite the original file or append the output to the end of the file (defaults to replace if not specified).
The process of using the SPOOL command is generally as follows:
- 1. Enter the SQLPLUS interface;
- 2. Use the `spool file_name` command to enable output logging;
- 3. Execute SQL query statements or other operations that require output results;
- 4. Use the `spool off` command to turn off output logging;
- 5. Exit the SQLPLUS interface, open the specified output file to view the result.
Notice:
The SPOOL command will only save the output results of the current connection to a file. If you want to record multiple query results or obtain results in different time periods, you must create and name different output files separately. At the same time, in some cases, issues such as file permissions and path legality need to be considered.
2. Operation steps
Ⅰ. Enter the SQLPLUS interface
Use the shortcut key [win+R] to open the run window, enter [cmd], and click OK or the Enter key [enter], as shown in the figure below:
Ⅱ. Switch to the drive letter folder you want to save. I will save it to the [SQL] folder of D drive here, and directly enter d: or D:, which is not case-sensitive.
Then enter cd sql to switch to the SQL file, and you can directly switch to this folder in one step, as shown in the figure:
Ⅲ. To connect to the database, enter sqlplus scott/tiger and press Enter, as shown in the figure:
Ⅳ. Enter the following commands in sequence:
First enter spool D:\SQL\dept.txt , which means to output the query results to the specified text;
Then enter the result query statement you want to output, such as querying all department table information select * form dept;
Finally, enter spool off; end this data export. The completion process is shown in the figure:
Ⅴ. After the output is finished, enter exit in the window to exit the SQLPLUS interface, as shown in the figure:
Ⅵ. Finally, we go to the folder of our choice to find the document we just exported, and then double-click to open it to view the data results, as shown in the figure below:
The data results in the text file are displayed correctly, and this data export is perfectly completed! ! !
3. The role of spool
Specific functions include:
- 1. Export query results: Use the SPOOL command to export SQL query results to files, which is convenient for users to perform operations such as data analysis and report generation.
- 2. Execution script log record: When the user executes the SQL script, the SPOOL command can save the output result of the script to a file, which is convenient for subsequent error checking, operation log confirmation, and modification record comparison.
- 3. SQL optimization check: Some startup statements disable the function of displaying the execution plan, so using the SPOOL command to output the execution plan information to a file can help users better understand the specific execution of the query, and perform performance detection and optimization.
- 4. Importing and migrating data: When performing operations such as database migration and backup, exporting query results to files can effectively improve data transmission efficiency and avoid data loss or damage.
Summarize:
The SPOOL command is a very handy automation tool for both database administrators and developers, reducing a lot of manual work and increased error.
In order to export data results quickly and conveniently, the data export in Oracle (2) will summarize an article about the use of spool command scripts, so stay tuned!