Oracle中处理duplicate的SQL技巧 在Oracle中处理重复数据的SQL技巧有以下几种方法: 使用DISTINCT关键字:可以通过在SELECT语句中使用DISTINCT关键字来去除重复的数据行。 SELECTDISTINCTcolumn1, column2FROMtable_name; 使用ROW_NUMBER()函数和Common Table Expressions(CTE):可以使用ROW_NUMBER()函数和CTE来为数据行添加行...
SQL>deletefromcz awhererowid<(selectmax(rowid) fromczwherec1=a.c1andc10=a.c10andc20=a.c20); (3).适用于有少量重复记录的情况(临时表法): SQL>createtabletestasselectdistinct*fromcz; (建一个临时表test用来存放重复的记录) SQL>truncatetablecz; (清空cz表的数据,但保留cz表的结构) SQL>insertinto...
SQL> select count(*) from dba_objects; COUNT(*) --- 73279 由于要在HR下建立个大表,要确保HR下的表空间足够大 QL> show user USER is "SYS" SQL> create table hr.test1 tablespace inventory as select * from dba_objects; Table created. Duplicate SQL 重复的SQL SQL Access Advisor: Overview Us...
SQL>alter table cz add constraint cz_unique unique(c1,c10,c20) exceptions into exceptions; * ERROR at line 1: ORA-02299: cannot validate (TEST.CZ_UNIQUE) - duplicate keys found SQL>create table dups as select * from cz where rowid in (select row_id from exceptions); Table created. SQL...
SYS@DGPHY1> select count(1) from lhr.test; COUNT(1) --- 1014 SYS@DGPHY1> 可以看到数据已经实时同步了,至此,物理备库搭建完成,至于备库的维护操作还有很多内容,参考我的其它blog。 实验总结 实验过程中需要注意的几项内容: 主库修改参数一定要加 sid='*' 监听必须配置好 执行duplicate命令的时候,如果...
10g查询并行执行模型从从属SQL模型移到并行独立游标模型。一个独立游标包含所有并行执行需要的信息,并将用在全部并行执行处理中。顺序执行变为并行执行,以及共享内存消耗的减少,并行独立游标的性能大幅度提升。 高速数据移动 10g 为数据的提取、加载以及转换提供了新的功能,以促进建立和刷新大型数据仓库或多个...
1当sql只使用一个json_value函数时,查询结果始终正确: select ID, json_value(json_field, '$.Code') from json_table where ID=390; select ID, json_value(json_field, '$.Time') from json_table where ID=390; 两条语句均只返回一条记录。
If record has a combination of duplicate id, addr, Ind and update_Date, select only one record from the duplicate records (It can be any record). Below was the expected result. Can anyone plug me some ideas to achieve this. here is the sqlfiddle:http://sqlfiddle.com/#!4/d0...
â Value Suppress suppresses duplicate values from displaying more than once. â Sort Ascending sorts the column in ascending order. â Sort Descending sorts the column in descending order. â Group adds a group header and footer for the column. â ...
SELECT*FROMfruits;Code language:SQL (Structured Query Language)(sql) As you can see from the picture above, thefruitstable has duplicate records with the same information repeated in bothfruit_nameandcolorcolumns. Finding duplicate rows using the aggregate function ...