在SQL中提取日期列的日期有多少种方法？

Question

select * from TNAME where
  to_char (tran_date,'YYYY') = 2018 

Answer 1

提取天？您的代码建议年，所以 - 我将使用年。以下是一些选项：

SQL> select count(*) from dual where extract(year from sysdate) = 2018;

  COUNT(*)
----------
         1

SQL> select count(*) from dual where to_char(sysdate, 'yyyy') = '2018';

  COUNT(*)
----------
         1

SQL> select count(*) from dual where trunc(sysdate, 'yyyy') = date '2018-01-01';

  COUNT(*)
----------
         1

SQL>