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oracle週數計算方法

從星期天開始起算

   Function Fn_GetWeekbyDate(P_Date Varchar2) Return Varchar2
   Is
   Begin
      Return To_char(To_Date(P_Date,'yyyy-mm-dd'),'fmww');
   End Fn_GetWeekbyDate;

從星期一開始起算
   Function Fn_GetWeekbyDate(P_Date Varchar2) Return Varchar2
   Is
   Begin
      Return To_char(To_Date(P_Date,'yyyy-mm-dd'),'fmiw');
   End Fn_GetWeekbyDate;

下面是一個有效引數列表to_char函式是用來轉換為一個字串的日期。這些引數可用於在多種組合。

Parameter Explanation
YEAR Year, spelled out
YYYY 4-digit year
YYY
YY
Y
Last 3, 2, or 1 digit(s) of year.
IYY
IY
I
Last 3, 2, or 1 digit(s) of ISO year.
IYYY 4-digit year based on the ISO standard
Q Quarter of year (1, 2, 3, 4; JAN-MAR = 1).
MM Month (01-12; JAN = 01).
MON Abbreviated name of month.
MONTH Name of month, padded with blanks to length of 9 characters.
RM Roman numeral month (I-XII; JAN = I).
WW Week of year (1-53) where week 1 starts on the first day of the year and continues to the seventh day of the year.
W Week of month (1-5) where week 1 starts on the first day of the month and ends on the seventh.
IW Week of year (1-52 or 1-53) based on the ISO standard.
D Day of week (1-7).
DAY Name of day.
DD Day of month (1-31).
DDD Day of year (1-366).
DY Abbreviated name of day.
J Julian day; the number of days since January 1, 4712 BC.
HH Hour of day (1-12).
HH12 Hour of day (1-12).
HH24 Hour of day (0-23).
MI Minute (0-59).
SS Second (0-59).
SSSSS Seconds past midnight (0-86399).
FF Fractional seconds.