SQL 基本函数 时间比较 常用语句

convert(char(10),train_time_endt,120) < '2010-01-01'

select to_char(sysdate,'YYYY-MM-DD HH12:MI:SS AM')from dual;

CAST('abc' AS varchar(5))

ISNULL(check_expression, replacement_value)
ISNULL(price, $10.00)

update table1 set unit_exec=u.units_Name from table2 u where u.user_Code = user_Code