现在一般对Oracle 分页查询实现如下 select * from ( select a.*,rownum r from ( 自己的sql ) a where rownum
现在一般对Oracle 分页查询实现如下
select * from (
select a.*,rownum r from (
自己的sql
) a where rownum ) where r > ?
如果这个sql 按一个含有重复值的字段排序
就会产生在不同页查出重复记录,并且某些记录查不到的现象(不是一定产生)
测试代码如下
CREATE TABLE TEST (
ID VARCHAR2(10) NOT NULL,
OD VARCHAR2(10) NULL
)
GO
--插入测试数据
insert into TEST
select level,case when levelgo
--测试分页结果
第1-5条
select * from (
select a.*,rownum r from (
select t1.id from TEST t1
order by t1.od desc
) a where rownum ) where r > 0
返回结果
行 ID R
1 4 1
2 8 2
3 7 3
4 6 4
5 5 5
第6-10条
select * from (
select a.*,rownum r from (
select t1.id from TEST t1
order by t1.od desc
) a where rownum ) where r > 5
返回结果
行 ID R
1 6 6
2 5 7
3 3 8
4 2 9
5 1 10
可以看到第一个结果集中id=5和id=6 在第二个结果集中也查到了 同时id=9 和id=10的记录都没查到
解决方案如下
如果出现满足上述两个条件的SQL
order by 后再加上表的主键;
如本例中
改为order by t1.od desc,t1.id 后现象消失
如果有更好的解决方法, 希望能告知= =
更多Oracle相关信息见Oracle 专题页面 ?tid=12

MySQLviewshavelimitations:1)Theydon'tsupportallSQLoperations,restrictingdatamanipulationthroughviewswithjoinsorsubqueries.2)Theycanimpactperformance,especiallywithcomplexqueriesorlargedatasets.3)Viewsdon'tstoredata,potentiallyleadingtooutdatedinforma

ProperusermanagementinMySQLiscrucialforenhancingsecurityandensuringefficientdatabaseoperation.1)UseCREATEUSERtoaddusers,specifyingconnectionsourcewith@'localhost'or@'%'.2)GrantspecificprivilegeswithGRANT,usingleastprivilegeprincipletominimizerisks.3)

MySQLdoesn'timposeahardlimitontriggers,butpracticalfactorsdeterminetheireffectiveuse:1)Serverconfigurationimpactstriggermanagement;2)Complextriggersincreasesystemload;3)Largertablesslowtriggerperformance;4)Highconcurrencycancausetriggercontention;5)M

Yes,it'ssafetostoreBLOBdatainMySQL,butconsiderthesefactors:1)StorageSpace:BLOBscanconsumesignificantspace,potentiallyincreasingcostsandslowingperformance.2)Performance:LargerrowsizesduetoBLOBsmayslowdownqueries.3)BackupandRecovery:Theseprocessescanbe

Adding MySQL users through the PHP web interface can use MySQLi extensions. The steps are as follows: 1. Connect to the MySQL database and use the MySQLi extension. 2. Create a user, use the CREATEUSER statement, and use the PASSWORD() function to encrypt the password. 3. Prevent SQL injection and use the mysqli_real_escape_string() function to process user input. 4. Assign permissions to new users and use the GRANT statement.

MySQL'sBLOBissuitableforstoringbinarydatawithinarelationaldatabase,whileNoSQLoptionslikeMongoDB,Redis,andCassandraofferflexible,scalablesolutionsforunstructureddata.BLOBissimplerbutcanslowdownperformancewithlargedata;NoSQLprovidesbetterscalabilityand

ToaddauserinMySQL,use:CREATEUSER'username'@'host'IDENTIFIEDBY'password';Here'showtodoitsecurely:1)Choosethehostcarefullytocontrolaccess.2)SetresourcelimitswithoptionslikeMAX_QUERIES_PER_HOUR.3)Usestrong,uniquepasswords.4)EnforceSSL/TLSconnectionswith

ToavoidcommonmistakeswithstringdatatypesinMySQL,understandstringtypenuances,choosetherighttype,andmanageencodingandcollationsettingseffectively.1)UseCHARforfixed-lengthstrings,VARCHARforvariable-length,andTEXT/BLOBforlargerdata.2)Setcorrectcharacters


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

Zend Studio 13.0.1
Powerful PHP integrated development environment

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
