fisql: 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 CentOS possible default full paths are:

/usr/bin/fisql - from package: freetds

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/fisql - from package: freetds-bin

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

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