Question

任何人都可以告诉我如何获取当月第一个日期到同月当前日期的列表吗？假设我想要获得2015年5月至2015年5月17日的第一个日期。

格式应该是这样的：ddmmyyyy

Answer 1

要获取从开始到当天的月份日期：

查询1 ：

SELECT TRUNC( SYSDATE, 'MM' ) + LEVEL - 1 AS DATE_OF_CURRENT_MONTH
FROM   DUAL
CONNECT BY LEVEL <= EXTRACT( DAY FROM SYSDATE )

<强> Results ：

| DATE_OF_CURRENT_MONTH |
|-----------------------|
| May, 01 2015 00:00:00 |
| May, 02 2015 00:00:00 |
| May, 03 2015 00:00:00 |
| May, 04 2015 00:00:00 |
|           .           |
|           .           |
|           .           |
| May, 15 2015 00:00:00 |
| May, 16 2015 00:00:00 |
| May, 17 2015 00:00:00 |

查询2 ：

WITH CTE( DATE_OF_CURRENT_MONTH, Lvl ) AS
(
  SELECT TRUNC( SYSDATE, 'MM' ), 1
  FROM DUAL
    UNION ALL
  SELECT TRUNC( SYSDATE, 'MM' ) + Lvl, Lvl + 1
  FROM CTE
  WHERE Lvl < EXTRACT( DAY FROM SYSDATE )
)
SELECT DATE_OF_CURRENT_MONTH FROM CTE

<强> Results ：

| DATE_OF_CURRENT_MONTH |
|-----------------------|
| May, 01 2015 00:00:00 |
| May, 02 2015 00:00:00 |
| May, 03 2015 00:00:00 |
| May, 04 2015 00:00:00 |
|           .           |
|           .           |
|           .           |
| May, 15 2015 00:00:00 |
| May, 16 2015 00:00:00 |
| May, 17 2015 00:00:00 |

要获得本月的所有日子：

查询3 ：

SELECT TRUNC( SYSDATE, 'MM' ) + LEVEL - 1 AS DATE_OF_CURRENT_MONTH
FROM   DUAL
CONNECT BY LEVEL <= EXTRACT( DAY FROM LAST_DAY( SYSDATE ) )

<强> Results ：

| DATE_OF_CURRENT_MONTH |
|-----------------------|
| May, 01 2015 00:00:00 |
| May, 02 2015 00:00:00 |
| May, 03 2015 00:00:00 |
| May, 04 2015 00:00:00 |
|           .           |
|           .           |
|           .           |
| May, 29 2015 00:00:00 |
| May, 30 2015 00:00:00 |
| May, 31 2015 00:00:00 |

查询4 ：

WITH CTE( DATE_OF_CURRENT_MONTH, Lvl ) AS
(
  SELECT TRUNC( SYSDATE, 'MM' ), 1
  FROM DUAL
    UNION ALL
  SELECT TRUNC( SYSDATE, 'MM' ) + Lvl, Lvl + 1
  FROM CTE
  WHERE Lvl < EXTRACT( DAY FROM LAST_DAY( SYSDATE ) )
)
SELECT DATE_OF_CURRENT_MONTH FROM CTE

<强> Results ：

| DATE_OF_CURRENT_MONTH |
|-----------------------|
| May, 01 2015 00:00:00 |
| May, 02 2015 00:00:00 |
| May, 03 2015 00:00:00 |
| May, 04 2015 00:00:00 |
|           .           |
|           .           |
|           .           |
| May, 29 2015 00:00:00 |
| May, 30 2015 00:00:00 |
| May, 31 2015 00:00:00 |

Answer 2

您可以connect by level伪列并通过将其结合到当前月份和年份来格式化此结果：

SELECT     TO_CHAR(LEVEL, '09') || TO_CHAR(SYSDATE, 'mmyyyy')
FROM       dual
CONNECT BY LEVEL < TO_NUMBER(TO_CHAR(SYSDATE, 'dd'))

编辑：
要显示当月的所有日期，您可以使用last_day功能检查当月的天数：

SELECT     TO_CHAR(LEVEL, '09') || TO_CHAR(SYSDATE, 'mmyyyy')
FROM       dual
CONNECT BY LEVEL < TO_NUMBER(TO_CHAR(LAST_DAY(SYSDATE), 'dd'))

如何在oracle中获得当月的第一个日期

2 个答案: