Oracle,将日期时间作为其当月的第一天

Question

我有一个日期变量,我想把它转换为它的第一天,

• 例如:10/10/2010 - > 01/10/2010
• 例如:31/07/2010 - > 01/07/2010

Answer 1

根据http://psoug.org/reference/date_func.html,这应该是花花公子......

SELECT TRUNC(yourDateField, 'MONTH') FROM yourTable

Answer 2

SQL> select to_date('31/07/2010', 'DD/MM/YYYY') from dual;

TO_DATE('
---------
31-JUL-10

SQL> select trunc(to_date('31/07/2010', 'DD/MM/YYYY'), 'MM') from dual;

TRUNC(TO_
---------
01-JUL-10

SQL>

Answer 3

select trunc(sysdate, 'mm') from dual;