Telling mysql to Read Queries from Other Programs

1.17.1 Problem

You want to shove the output from another program into mysql.

1.17.2 Solution

Use a pipe.

1.17.3 Discussion

An earlier section used the following command to show how mysql can read SQL statements from a file:

% mysql cookbook < limbs.sql

mysql can also read a pipe, to receive output from other programs as its input. As a trivial example, the preceding command is equivalent to this one:

% cat limbs.sql | mysql cookbook

Before you tell me that I've qualified for this week's "useless use of cat award,"[5] allow me to observe that you can substitute other commands for cat. The point is that any command that produces output consisting of semicolon-terminated SQL statements can be used as an input source for mysql. This can be useful in many ways. For example, the mysqldump utility is used to generate database backups. It writes a backup as a set of SQL statements that recreate the database, so to process mysqldump output, you feed it to mysql. This means you can use the combination of mysqldump and mysql to copy a database over the network to another MySQL server:

[5] Under Windows, the equivalent would be the "useless use of type award":

% mysqldump cookbook | mysql -h some.other.host.com cookbook

Program-generated SQL also can be useful when you need to populate a table with test data but don't want to write the INSERT statements by hand. Instead, write a short program that generates the statements and send its output to mysql using a pipe:

% generate-test-data | mysql cookbook

1.17.4 See Also

mysqldump is discussed further in Chapter 10.