select t.sj ,count(1) from (select to_date(to_char(CZSJ,'yyyy-mm-dd') ,'yyyy-mm-dd) ') sj from 表名) t group by SJ;
SELECT CREATED FROM USER_OBJECTS WHERE OBJECT_NAME='RW_YJGXQ_102994_TJ';
delete 表名 a where not exists ( select 1 from (select min(rowid) row_id from 表名 group by sfzh)t where t.row_id=a.rowid);
5、刪除表
drop table 表名;
6、clob轉換成varchar 類型to_char(substr(字段名,1,1000));
7、將字節轉換爲M
String wjdx = "1024000000";
double Dwjdx = Double.parseDouble(wjdx);
BigDecimal filesize = new BigDecimal(Dwjdx);
BigDecimal megabyte = new BigDecimal(1024 * 1024);
float Mwjdx = filesize.divide(megabyte, 2, BigDecimal.ROUND_UP).floatValue();
String wjdx_m = Mwjdx + ""; //轉換爲MB
8、代碼執行時間計算
Date start = new Date();
System.out.println("執行代碼段");
Date end = new Date();
double XHSJ = (end.getTime()-start.getTime())/1000.0;
System.out.println("消耗時間:"+XHSJ+"秒");
9、用戶名註冊正則
^[a-zA-Z0-9][\\-0-9a-zA-Z_@\\.]{4,19}$用戶名必須由數字、字母(區分大小寫)或字符('_'、'-'、@、'.')(點)組成,長度爲5-20位,並且以字母或數字開頭
10、11位手機號校驗
^1[3|4|5|8][0-9]\\d{8}$
11、js中Object轉字符串
JSON.stringify(object)
或者toString();
12、字符串轉Object
JSON.parse(str)
13、mysql查詢
13.1、查詢列名:
show columns from app_user;
13.2、先截取再聚合
SELECT count(1) count,substring(r.ParentURL,1,locate(r.Domain,r.ParentURL,3)+char_length(r.Domain)) name from Resource r WHERE r.Domain='xxx.cn' GROUP BY name ORDER BY count DESC ;