我正在尝试查询数据库以验证是否存在注册表。我创建了bash脚本来实现这一点：

read -p "`echo $'\n '`-------------`echo $'\n '` Insert a CPF: `echo $'\n '`-------------`echo $'\n '`" CPF
USER_IN_OPTOUT=$(mysql -u $BMB_MYSQL_USER -h $BMB_MYSQL_HOST -NB -se "SELECT cpf FROM optout WHERE cpf = $CPF;")
if [[ ${USER_IN_OPTOUT} == *"${CPF:0}"* ]]; then
    echo "----------------------------------------"
    echo "User already exists."
    echo "----------------------------------------"
else
    echo "---------------------------------------"
    echo "User does not exists."
    echo "---------------------------------------"
    exit 1
fi

变量CPF（$CPF）等于00324323721。由于存在此注册表，它会按预期返回cpf。但是，此查询正在删除返回324323721的前导零。我希望收益完全是00324323721。我该怎么办？