Mysql query to update multiple rows using a input file from linux - mysql

Question

I'm trying to update multiple rows in a DB using a small script.
I need to update the rows based on some specific user_ids which I have in a list on Linux machine.
#! /bin/bash
mysql -u user-ppassword db -e "update device set in_use=0 where user_id in ()";
As you see above, the user_ids are in a file, let's say /opt/test/user_ids_txt.
How can I import them into this command?

Answer 1

This really depends on the format of user_ids_txt. If we assume it just happens to be in the correct syntax for your SQL in statement, the following will work:
#! /bin/bash
mysql -u user-ppassword db -e "update device set in_use=0 where user_id in ($(< /opt/test/user_ids_txt))";
The bash interpreter will substitute in the contents of the file. This can be dangerous for SQL queries, so I would echo out the command on the terminal to make sure it is correct before implementing it. You should be able to preview your SQL query by simply running the following on the command line:
echo "update device set in_use=0 where user_id in ($(< /opt/test/user_ids_txt))"
If your file is not in the SQL in syntax you will need to edit it (or a copy of it) before running your query. I would recommend something like sed for this.
Example
Let's say your file /opt/test/user_ids_txt is just a list of user_ids in the format:
aaa
bbb
ccc
You can use sed to edit this into the correct SQL syntax:
sed 's/^/\'/g; s/$/\'/g; 2,$s/^/,/g' /opt/test/user_ids_txt
The output of this command will be:
'aaa'
,'bbb'
,'ccc'
If you look at this sed command, you will see 3 separate commands separated by semicolons. The individual commands translate to:
1: Add ' to the beginning of every line
2: Add ' to the end of every line
3: Add , to the beginning of every line but the first
Note: If your ID's are strictly numeric, you only need the third command.
This would make your SQL query translate to:
update device set in_use=0 where user_id in ('aaa'
,'bbb'
,'ccc')
Rather than make a temporary file to store this, I would use a bash variable, and simply plug that into the query like this:
#! /bin/bash
in_statement="$(sed 's/^/\'/g; s/$/\'/g; 2,$s/^/,/g' /opt/test/user_ids_txt)"
mysql -u user-ppassword db -e "update device set in_use=0 where user_id in (${in_statement})";