select (hours+minutes+seconds) AS total_seconds from ( select to_char(sysdate,('HH24'))*60*60 AS hours, to_char(sysdate,('mi'))*60 AS minutes, to_char(sysdate,'ss') AS seconds from A );
解讀:
AS:是給前面的結果指定一個新的列
HH21:時
mi:分
ss:秒
算出小時和分鍾的秒數,然后秒就不用算了,在后面直接相加,hours+minutes+seconds,指定給新的列total_seconds