假设你给定的时间是字符串,否则可以不用to_char
SELECT FIELD_DATETIME FROM
(SELECT FIELD_DATETIME FROM TABLE_NAME
WHERE TO_CHAR(FIELD_DATETIME,'YYYY/MM/DD') < m_DateTime
ORDER BY FIELD_DATETIME DESC )
WHERE ROWNUM = 1
SELECT FIELD_DATETIME FROM
(SELECT FIELD_DATETIME FROM TABLE_NAME
WHERE TO_CHAR(FIELD_DATETIME,'YYYY/MM/DD') < m_DateTime
ORDER BY FIELD_DATETIME DESC )
WHERE ROWNUM = 1
where Field_DateTime =
(select MAX(Field_DateTime ) from tabnamae where Field_DateTime <= m_DateTime )