Download e-book for kindle: MySQL Cookbook by DuBois P.

By DuBois P.

MySQL Cookbook offers a distinct problem-and-solution layout that gives sensible examples for daily programming dilemmas. for each challenge addressed within the publication, there is a worked-out answer or "recipe" - brief, targeted items of code that you should insert at once into your functions. greater than a set of cut-and-paste code, this booklet rationalization how and why the code works, so that you can learn how to adapt the options to comparable occasions.

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Sh makes sure that exactly one argument was provided, then uses it as a table name in a row-counting query. sh limbs Rows in table: 12 Variable substitution can be helpful for constructing queries, but you should use this capability with caution. sh "limbs;DROP TABLE limbs" 59 60 In that case, the resulting query input to mysql becomes: SELECT COUNT(*) AS 'Rows in table:' FROM limbs;DROP TABLE limbs; This input counts the table rows, then destroys the table! For this reason, it may be prudent to limit use of variable substitution to your own private scripts.

If you assign a value to a variable using a statement that returns multiple rows, the value from the last row is used: 37 38 mysql> SELECT @name := thing FROM limbs WHERE legs = 0; +----------------+ | @name := thing | +----------------+ | squid | | octopus | | fish | | phonograph | +----------------+ mysql> SELECT @name; +------------+ | @name | +------------+ | phonograph | +------------+ If the statement returns no rows, no assignment takes place and the variable retains its previous value. 00 sec) mysql> SELECT @name2; +--------+ | @name2 | +--------+ | NULL | +--------+ To set a variable explicitly to a particular value, use a SET statement.

Bat), so chmod is unnecessary. Also, the command interpreter includes the current directory in its search path by default, so you should be able to invoke programs that are located there without specifying any leading path. 4 Writing Shell Scripts Under Unix Here is a shell script that reports the current uptime of the MySQL server. It runs a SHOW STATUS query to get the value of the Uptime status variable that contains the server uptime in seconds: #! sh - report server uptime in seconds mysql -B -N -e "SHOW STATUS LIKE 'Uptime'" The first line of the script that begins with #!

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