Chapter 6 Using mysql in Batch Mode

In the previous sections, you used mysql interactively to enter statements and view the results. You can also run mysql in batch mode. To do this, put the statements you want to run in a file, then tell mysql to read its input from the file:

$> mysql < batch-file

If you are running mysql under Windows and have some special characters in the file that cause problems, you can do this:

C:\> mysql -e "source batch-file"

If you need to specify connection parameters on the command line, the command might look like this:

$> mysql -h host -u user -p < batch-file
Enter password: ********

When you use mysql this way, you are creating a script file, then executing the script.

If you want the script to continue even if some of the statements in it produce errors, you should use the --force command-line option.

Why use a script? Here are a few reasons:

• If you run a query repeatedly (say, every day or every week), making it a script enables you to avoid retyping it each time you execute it.

• You can generate new queries from existing ones that are similar by copying and editing script files.

• Batch mode can also be useful while you are developing a query, particularly for multiple-line statements or multiple-statement sequences. If you make a mistake, you do not have to retype everything. Just edit your script to correct the error, then tell mysql to execute it again.

• If you have a query that produces a lot of output, you can run the output through a pager rather than watching it scroll off the top of your screen:

  $> mysql < batch-file | more

• You can catch the output in a file for further processing:

  $> mysql < batch-file > mysql.out

• You can distribute your script to other people so that they can also run the statements.

• Some situations do not allow for interactive use, for example, when you run a query from a cron job. In this case, you must use batch mode.

The default output format is different (more concise) when you run mysql in batch mode than when you use it interactively. For example, the output of SELECT DISTINCT species FROM pet looks like this when mysql is run interactively:

+---------+
| species |
+---------+
| bird    |
| cat     |
| dog     |
| hamster |
| snake   |
+---------+

In batch mode, the output looks like this instead:

species
bird
cat
dog
hamster
snake

If you want to get the interactive output format in batch mode, use mysql -t. To echo to the output the statements that are executed, use mysql -v.

You can also use scripts from the mysql prompt by using the source command or \. command:

mysql> source filename;
mysql> \. filename

See Executing SQL Statements from a Text File, for more information.