bash using variables in mysql from cmdline

Question

Say I have a number of similar mysql databases, where one table consists of users, which I want to query, while the name of the specific table is also variable.

I would say I need something similar, but it gives me a hard time to get the quotes rigth:

user_id = $(mysql --user=$dba --password=$dbp $dbn -e "SELECT id FROM ${user_tbl} WHERE username = \"guest\"")

Addition: Ok, now knowing what the initial query should have been, comes the other question, how to update a field again using a variable for the tabelname.

mysql --user=$dba --password=$dbp $dbn -e "UPDATE ${user_tbl} SET password=${pass} WHERE username = 'guest'"
gives the following error: Unknown column 'some_encrypted_pass' in 'field list'

... WHERE username = "guest" is not valid in any SQL. Simply making that a valid SQL would have solved your problem instantly. ... WHERE username = 'guest' — janos
– janos, Commented Oct 19, 2013 at 10:28

chepner · Accepted Answer · 2013-10-19 13:32:35Z

1

user_id=$(mysql --user=$dba --password=$dbp $dbn -e "SELECT id FROM ${user_tbl} WHERE username = 'guest'")

you should use single quote to search guest string.

btw, why are you using that method, simply run mysqli_query and get value in array [with fetch methods] ? that will be better and more secure and reliable.

edited Oct 19, 2013 at 13:32

chepner

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answered Oct 19, 2013 at 10:04

Sumit Gupta

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3 Comments

slibbe Over a year ago

Thank you. Been trying so many combinations of double quotes, single quotes with or without backslashes, that I nearly lost my sight.

Sumit Gupta Over a year ago

yes, I thought you are using PHP code, my bad. but you can use php for easy coding if you know it.

slibbe Over a year ago

Well, in the end I concluded that variables for tablenames are possible to some extend, and impossible beyond. So it may be time to change for PHP/Perl/Python or the like for this sort of system utilities. I was using bash :)

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