Oracle 中date类型精确可以年月日，时分秒，timestamp类型可以精确的秒以下
data转为timstamp
# to_timestamp函数 Select to_timestamp('2006-01-01 12:10:10.1','yyyy-mm-dd hh24:mi:ss.ff') From dual;
timestamp转化为data
# timestamp+0 select Systimestamp+0 FROM DUAL; # to_char函数 Select to_char(Systimestamp,'yyyymmdd') From dual; # cast转化 Select Cast(Systimestamp As Date) From dual;
