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>altertableczaddconstraint cz_uniqueunique(c1,c10,c20) exceptionsintoexceptions; * ERROR at line1: ORA-02299: cannot validate (TEST.CZ_UNIQUE)-duplicate keys found SQL>createtabledupsasselect *fromczwhererowidin(selectrow_idfromexceptions); Tablecreated. SQL>select*fromdups; C1 C10 C20 ---...
SELECT tablespace_name FROM all_tables WHERE table_name = 'YOURTABLENAME'; 18 How to remove duplicate rows from a table If the unique/primary keys can be identified from the table, it is easier to remove the records from the table using the following query: DELETE FROM tablename WHERE row...
{ allocate channel ch001 type disk; allocate channel ch002 type disk; allocate channel ch003 type disk; allocate channel ch004 type disk; allocate auxiliary channel ch005 type disk; duplicate target database for standby nofilenamecheck from active database DORECOVER spfile set db_unique_name='...
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...
共享SQL区是存放用户SQL命令的区域,数据字典缓冲区存放数据库运行的动态信息 缓冲区高速缓存:Database Buffer Cache用于缓存从数据文件中检索出来的数据块,可以大大提高查询和更新数据的性能 大型池:Large Pool是SGA中一个可选的内存区域,它只用于shared server环境 ...
The button functions include: 3-12 Oracle Fusion Middleware User's Guide for Oracle Business Activity Monitoring Saving Reports â Group Sort and Value Suppress sorts by group and suppresses duplicate values from displaying. â Value Suppress suppresses duplicate values from displaying...
Oracle sql动态比较表/数据集中的行 您可以使用简单的group by+having子句: select idfrom twhere dt>=sysdate-3group by idhaving count(distinct result)=1 -- just one distinct `result`and count(*)=3 -- only 3 rows >= sysdate-3and count(distinct dt)=3 -- all 3 days are present; 带测试...
DISTINCT eliminates the duplicate rows. The INTO clause and the items that follow it in the command syntax are optional, because Microsoft SQL Server allows SELECT statements without FROM clauses as can be seen in the following example: SELECT getdate() SELECT...INTO allows you to insert the...