0. 修改mysql数据库中tinyint为smallint pgloader默认会把mysql的tinyint字段转为boolean字段，如果需

count(1), count(*), count(column)区别 count(1)和count(*)是相同的, 但count(*)代表的语义更明确 COUNT(<expression>) 统计非空值个数 使用IN时是

导出数据 mysqldump -u username -p database_name > data-dump.sql reference 4 Ways to Insert Multiple Rows in Oracle

不使用Batch Insert -- 使用mybatis时，下面的做法当一次插入数量太多时会报错（ORA-00913: too many values），这时需要用batch

在线执行环境，缺点是需要注册 Oracle live SQL http://sqlfiddle.com/ 创建用户 alter session set "_ORACLE_SCRIPT"=true; CREATE USER TOM IDENTIFIED BY a12345678; GRANT CONNECT, RESOURCE, DBA TO TOM; GRANT select on tom.contacts TO TOM; REVOKE DBA FROM TOM; REVOKE select on tom.contacts FROM TOM; DROP USER TOM; -- 同时删除用户下的所有对象

查找lock select * from master.dbo.sysprocesses where DB_NAME(dbid)=’test’ and spid<>@@SPID; exec sp_lock exec sp_who2 SPID; select request_session_id, resource_type, resource_description, request_mode, request_status, request_owner_type from sys.dm_tran_locks; kill SPID; 查看表结构 SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'yourTableName'; 日期 -- 当前时