Tips for Interacting with mysql
This section discusses how to interact with the
client program more
Simplifying the Connection Process
When you invoke mysql , it's likely that you need to specify connection parameters such as hostname, username, or password. That's a lot of typing just to run a program, and it gets tiresome very quickly. There are several ways to minimize the amount of typing necessary to establish a connection to the MySQL server:
Using an Option File
MySQL allows you to store connection parameters in an option file. Then you don't have to type the parameters each time you run
; they are used just as if you had entered them on the command line. A big advantage of this technique is that the parameters can also be used by other MySQL
Under Unix, you set up an option file by creating a file named ~/.my.cnf (that is, a file named .my.cnf in your home directory). Under Windows, create an option file named my.ini in your Windows directory or named my.cnf in the root directory of the C drive (that is, %WINDIR%\my.ini or C:\my.cnf ). An option file is a plain text file; you can create it using any text editor. The file's contents should look something like this:
[client] host= server_host user= your_name password= your_pass
line signals the beginning of the
option group. MySQL programs read the lines following it to obtain option values, until the end of the file or until a different option
[client] host=cobra.snake.net user=sampadm password=secret
line is required, to define where the option group begins, but the lines that define parameter values are optional; you can specify just the ones you need. For example, if you're using Unix and your MySQL username is the same as your Unix login
Under Unix, an additional precaution that you should take after creating the option file is to set its access mode to a
% chmod 600 .my.cnf % chmod u=rw,go-rwx .my.cnf
Using Your Shell's Command History
Using Shell Aliases and Scripts
If your shell provides an alias facility, you can set up a short command name that maps to a long command. For example, in csh or tcsh , you can use the alias command to set up an alias named sampdb like this:
alias sampdb 'mysql -h cobra.snake.net -p -u sampadm sampdb'
The syntax for bash is slightly different:
alias sampdb='mysql -h cobra.snake.net -p -u sampadm sampdb'
Defining the alias makes the following two commands equivalent:
% sampdb % mysql -h cobra.snake.net -p -u sampadm sampdb
Clearly, the first is easier to type than the second. To make the alias take effect each time you log in, put the alias command in one of your shell's startup files (for example, .tcshrc for tcsh , or .bash_profile for bash ).
Under Windows, a similar technique is to create a shortcut that points to the mysql program, and then edit the shortcut's properties to include the appropriate connection parameters.
Another way to invoke commands with less typing is to create a script that executes mysql for you with the proper options. In Unix, a shell script that is equivalent to the sampdb alias just shown looks like this:
#! /bin/sh exec mysql -h cobra.snake.net -p -u sampadm sampdb
If you name the script sampdb and make it executable (with chmod +x sampdb ), you can type sampdb at the command prompt to run mysql and connect to the sampdb database.
Under Windows, a batch file can be used to do the same thing. Name the file sampdb.bat and put the following line in it:
mysql -h cobra.snake.net -p -u sampadm sampdb
This batch file can be run either by typing sampdb at the prompt in a DOS console or by double-clicking its Windows icon.
If you need to access several databases or connect to several
Issuing Statements with Less Typing
is an extremely useful program for interacting with your database, but its interface is most suitable for short, single-line queries. It's true that
itself doesn't care whether a query
Using the mysql Input Line Editor
has the GNU Readline library built in to allow input line editing. You can manipulate the line you're currently entering, or you can recall previous input lines and re-enter them, either as is or after further modification. This is
Some of the key sequences you will find useful are shown in Table 1.4, but there are many input editing commands available in addition to those shown in the table. You can read about them in the command editing chapter of the bash manual, available online from the GNU Project Web site at http://www.gnu.org/manual/.
Table 1.4. mysql Input Editing Commands
The following example describes a simple use for input editing. Suppose that you've entered this query while using mysql :
mysql> SHOW COLUMNS FROM persident;
If you notice that you've
If you press Enter before you notice the misspelling, that's not a problem. After mysql displays its error message, press Up arrow or Ctrl-P to recall the line, and then edit it as just described.
Under Windows, the Readline editing capabilities are not available in mysql . If you're using a Windows NT-based system, mysql supports the arrow keys for moving up and down through input lines or left and right within lines, but not the other editing commands.
Using Copy and Paste to Issue Statements
If you work in a windowing environment, the text of statements that you find useful can be saved in a file and recalled by copy and paste operations. Simply follow this procedure:
The procedure sounds cumbersome when written out like that, but when you're actually carrying it out, it provides a way to enter statements quickly and with no typing. With a little practice, it becomes second nature.
You can use copy and paste in the other direction, too (from your terminal window to your statement file). On Unix, when you enter statements in mysql , they are saved in a file named .mysql_history in your home directory. If you manually enter a statement that you want to save for further reference, quit mysql , open .mysql_history in an editor, and then copy and paste the statement from .mysql_history into your statement file.
Running mysql in Batch Mode
It's not necessary to run
can read input from a file in non-interactive (batch) mode. This is useful for statements that you run periodically because you
Suppose that you have a query that finds Historical League
SELECT last_name, first_name, email, interests FROM member WHERE interests LIKE '%depression%' ORDER BY last_name, first_name;
Put the query in a file interests.sql , and then execute it by feeding it to mysql like this:
% mysql sampdb < interests.sql
By default, mysql produces output in tab-delimited format when run in batch mode. If you want the same kind of table-format output you get when you run mysql interactively, use the -t option:
% mysql -t sampdb < interests.sql
If you want to save the output, redirect it to a file:
% mysql -t sampdb < interests.sql > output_file
If you are already running mysql , execute the contents of the file by using a source command:
mysql> source interests.sql
To use the query to find members with an interest in Thomas Jefferson, you could edit the query file to change depression to Jefferson and then run mysql again. That works okay as long as you don't use the query very often. If you do, a better method is needed. One way to make the query more flexible is to put it in a shell script that takes an argument from the script command line and uses it to change the text of the query. That parameterizes the query so that you can specify the interests value when you run the script. To see how this works, write a little shell script, interests.sh :
#! /bin/sh # interests.sh - find USHL members with particular interests if [ $# -ne 1 ]; then echo 'Please specify one keyword'; exit; fi mysql -t sampdb <<QUERY_INPUT SELECT last_name, first_name, email, interests FROM member WHERE interests LIKE '%%' ORDER BY last_name, first_name; QUERY_INPUT
The third line makes sure that there is one argument on the command line; it prints a short message and exits
Before you can run the script, you must make it executable:
% chmod +x interests.sh
Now you don't need to edit the script each time you run it. Just tell it what you're looking for on the command line:
% ./interests.sh depression % ./interests.sh Jefferson
The interests.sh script is located in the misc directory of the sampdb distribution. An equivalent Windows batch file, interests.bat , is provided there as well.