db_sql: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/db_sql - from package: db-util

You may install the required package with command apt-get install {package}

Error in other languages:
db_sql: bevel nie gevind nie
db_sql: comandă negăsită
db_sql: comando não encontrado
db_sql: commande introuvable
db_sql: command not found
db_sql: käsku ei ole
db_sql: không tìm thấy lệnh
db_sql: komanda nerasta
db_sql: Kommando nicht gefunden.
db_sql: kommandot finns inte
db_sql: komut yok
db_sql: nie znaleziono polecenia
db_sql: níor aimsíodh an t-ordú
db_sql: no se encontró la orden
db_sql: no s'ha trobat l'ordre
db_sql: opdracht niet gevonden
db_sql: parancs nem található
db_sql: perintah tidak ditemukan
db_sql: príkaz nenájdený
db_sql: příkaz nenalezen
db_sql: команда не найдена
db_sql: командата не е открита
db_sql: 命令找不到
db_sql: コマンドが見つかりません