ALTER SYSTEM FLUSH SHARED_POOL;ALTER SYSTEM FLUSH BUFFER_CACHE;ALTER SYSTEM FLUSH GLOBAL CONTEXT;

hive有一个获得当前时区的UNIX时间戳：unix_timestamp语法: unix_timestamp()返回值: bigint说明: 获得当前时区的UNIX时间戳selectunix_timestamp() ；我们需要的不是时间戳而是具体的当前时间：from_unixtime语法: from_unixtime(bigint unixtime[, string format])举例：sele

select regexp_replace(reflect("java.util.UUID", "randomUUID"), "-", "") uuid

select regexp_replace(NVL(" 132 1234 6250 ",''),'[\\s]+|[\\u3000]+|[\,]','');

方法一：select field1,listagg(field3,',') within GROUP (order by field3) from test group by field1;方法二（在方法一报出所拼接的字符串长度过长时，使用方法二）：select field1,xmlagg(xmlparse(content field3||',' wellformed) order by fiel

mysql时间操作获取当前时间select now();2022-01-15 15:31:34.0获取当前时间的前1天时间select DATE_SUB(CURRENT_TIMESTAMP,INTERVAL 1 day)；可选值如下：字符串转dateselect str_to_date(DATE_SUB(now(),INTERVAL 0 day),'%Y-%m-%d %H:%i:%s')；时间格式

一千万数据量所需时间16分钟左右两千万数据量所需时间

SELECT (SYSDATE - TO_DATE('1970-1-1 8', 'YYYY-MM-DD HH24')) * 86400000 + TO_NUMBER(TO_CHAR(SYSTIMESTAMP(3), 'FF')) AS MILLIONS FROM DUAL;

select sys_guid() from dual

--表空间CREATE TABLESPACE sdtDATAFILE 'F:\tablespace\demo' size 800MEXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO;--索引表空间CREATE TABLESPACE sdt_IndexDATAFILE 'F:\tablespace\demo' size 512MEXTENT M