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TO_CHAR函数的Oracle / PLSQL，数字或日期转换为一个字符串。
to_char函数的语法是：
to_char( value, [ format_mask ], [ nls_language ] )
值可以是数字或日期将被转换为一个字符串。
format_mask是可选的。这是将要使用的格式转换成一个字符串值。
NLS_LANGUAGE是可选的。这是免入息审查贷款计划的语言，用于转换为字符串的值。
Applies To:
代码如下Oracle 8i, Oracle 9i, Oracle 10g, Oracle 11g
实例
to_char(1210.73, "9999.9") would return "1210.7"
to_char(1210.73, "9,999.99") would return "1,210.73"
to_char(1210.73, "$9,999.00") would return "$1,210.73"
to_char(21, "000099") would return "000021"
日期实例
下面是一个有效参数列表to_char函数是用来转换为一个字符串的日期。这些参数可用于在多种组合。
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.
The following are date examples for the to_char function.
代码如下 to_char(sysdate, "yyyy/mm/dd"); would return "2003/07/09"
to_char(sysdate, "Month DD, YYYY"); would return "July 09, 2003"
to_char(sysdate, "FMMonth DD, YYYY"); would return "July 9, 2003"
to_char(sysdate, "MON DDth, YYYY"); would return "JUL 09TH, 2003"
to_char(sysdate, "FMMON DDth, YYYY"); would return "JUL 9TH, 2003"
to_char(sysdate, "FMMon ddth, YYYY"); would return "Jul 9th, 2003"
你会发现，在一些例子中，format_mask参数与“FM”开始。这意味着，零和空格被抑制。这在下面的例子可以看出。
代码如下to_char(sysdate, "FMMonth DD, YYYY"); would return "July 9, 2003"
to_char(sysdate, "FMMON DDth, YYYY"); would return "JUL 9TH, 2003"
to_char(sysdate, "FMMon ddth, YYYY"); would return "Jul 9th, 2003"