Oracle TO_DATE() 用法
2011-08-18 11:45 calm_水手 阅读(768) 评论(0) 编辑 收藏 举报In Oracle/PLSQL, the to_date function converts a string to a date.
The syntax for the to_date function is:
to_date( string1, [ format_mask ], [ nls_language ] )
string1 is the string that will be converted to a date.
format_mask is optional. This is the format that will be used to convert string1 to a date.
nls_language is optional. This is the nls language used to convert string1 to a date.
The following is a list of options for the format_mask parameter. These parameters can be used in many combinations.
| 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 |
| RRRR | Accepts a 2-digit year and returns a 4-digit year. A value between 0-49 will return a 20xx year. A value between 50-99 will return a 19xx year. |
| 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. Use a value from 1 to 9 after FF to indicate the number of digits in the fractional seconds. For example, 'FF4'. |
| AM, A.M., PM, or P.M. | Meridian indicator |
| AD or A.D | AD indicator |
| BC or B.C. | BC indicator |
| TZD | Daylight savings information. For example, 'PST' |
| TZH | Time zone hour. |
| TZM | Time zone minute. |
| TZR | Time zone region. |
