Recipe 1.16. Preventing Query Output from Scrolling off the Screen

Problem

Query output zooms off the top of your screen before you can see it.

Solution

Tell mysql to display output a page at a time, or run mysql in a window that allows scrollback.

Discussion

If a statement produces many lines of output, normally the lines just scroll right off the top of the screen. To prevent this, tell mysql to present output a page at a time by specifying the --pager option.^[] --pager = program tells mysql to use a specific program as your pager:

^[] The --pager option is not available under Windows.

% mysql --pager=/usr/bin/less             

--pager by itself (with no option value) tells mysql to use your default pager, as specified in your PAGER environment variable:

% mysql --pager             

If your PAGER variable isn't set, you must either define it or use the first form of the command to specify a pager program explicitly. To define PAGER, use the instructions given in Appendix B for setting environment variables.

Within a mysql session, you can turn paging on or off using \P or \n, respectively. \P without an argument enables paging using the program specified in your PAGER variable. \P with an argument enables paging using the argument as the name of the paging program:

mysql> \P PAGER set to /bin/more mysql> \P /usr/bin/less PAGER set to /usr/bin/less mysql> \n PAGER set to stdout 

Another way to deal with long result sets is to use a terminal program that allows you to scroll back through previous output. Programs such as xterm for the X Window System, Terminal for Mac OS X, or the console window for Windows allow you to set the number of output lines saved in the scrollback buffer. Under Windows, you can set up a console window that allows scrollback by using the following procedure:

1. Locate the Console item in the Control Panel or cmd.exe in the following directory: WINDOWS\system32.

2. Create a shortcut to the item by right-clicking on it and dragging the mouse to where you want to place the shortcut (on the desktop, for example).

3. Right-click on the shortcut, and select the Properties item from the menu that appears.

4. Select the Layout tab in the resulting Properties window.

5. Set the screen buffer height to the number of lines you want to save, and click the OK button.

Now you can launch the shortcut to get a scrollable console window that allows output produced by commands in that window to be retrieved using the scrollbar.