2014-06-20 Created By BaoXinjian DBA常用的SQL汇总 1.监控索引是否使用 alter index&index_name monitoring usage;alter index&index_name nomonitoring usage;select*from v$object_usage where index_name=index_name;2.求数据文件的I/...
笛卡尔积,两个字段汇总到一张表(有无关联字段无所谓)并且要标记出哪个表数据量少,放在MAPJOIN的注释中;SELECT /*+MAPJOIN(t_2)*/t_1.col_1 AS col_1, t_2.col_2 AS col_2 FROM t_xxxx AS t_1, t_yyyy AS t_2...