linux 变量作为参数传递给sql

```powershell
function c(){
    cnt=`sqlplus -s USERNAME/PASSWORD  << EOF
    SET FEEDBACK OFF
    SET HEADING  OFF
    SELECT NVL(COUNT(*) , 0) FROM a WHERE as='${K}';
    exit
    quit
EOF
    `
    echo $cnt
}

EOF前后不能有空格
'${K}'一定要带上单引号