Bash script runs manually, but fails on crontab

Another more generic way is to have cron run the user's bash logon process. In addition to the PATH, this will also pick up any LD_LIBRARY_PATH, LANG settings, other environment variables, etc. To do this, code your crontab entry like:

34  12  * * *   bash -l /home/db-backup/mysqlbackup.sh

The problem is probably that your $PATH is different in the manual environment from that under which crontab runs. Hence, which can't find your executables. To fix this, first print your path in the manual environment (echo $PATH), and then manually set up PATH at the top of the script you run in crontab. Or just refer to the programs by their full path.

Edit: Add this near the top of your script, before all the which calls:

export PATH="/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/mysql/bin:/opt/android-sdk-linux/tools:/opt/android-sdk-linux/platform-tools:~/usr/lib/jvm/jdk-6/bin"