search
HomeDatabaseMysql Tutorial对Oracle存储过程的几点认识

1、写Oracle存储过程时最好不要在其中写Commit语句。一般调用程序会自动Commit数据,比如用NHibernate调用的时候,NHibernate就会自动Commi

1、写Oracle存储过程时最好不要在其中写Commit语句。

一般调用程序会自动Commit数据,,比如用NHibernate调用的时候,NHibernate就会自动Commit数据。如果写了,会造成NHibernate调用完存储过程之后抛出错误。

2、重视Count的特殊比较作用。

在一个Select语句中,用Count对不同的字段进行统计,如果某行数据中被统计字段值为null,不会计入该字段统计值。利用这一点可以进行多表关联统计,比较数据的一致性。

例如:

Select Count(dmc.id) dmcCnt, Count(dmp.id) dmpCnt,

Count(Case dmp.type When 1 Then 1 Else null End) dmp2, Count(dmt.id) dmtCnt

Into i_Count1, i_Count2, i_Count3, i_Count4

From dmc

left join dmp on dmp.id = dmc.dmpid

and dmp.procdoctimestamp = dmc.procdoctimestamp

left join dmt on dmt.dmpid = dmp.id

3、通过关联数据更新一个表时,要注意关联数据的唯一性。

例如:

update (

select dmu.cu, dmu.lmt,

dmcl.cu cu1, dmcl.lmt lmt1

from dmu, dmcl, dmp

where dmu.id = dmp.dmuid

and dmcl.dmpid = dmproc.id

and dmcl.id = dmu.dmclid

)

Set cu = cu1,

lmt = lmt1;

此语句中的dmu表中必须要有dmcl表的主关键字段才可以唯一确定cu1和lmt1的值,否则Oracle会认为你使用多条数据更新一条数据,那样是不允许的。有一些朋友使用一个表的数据更新另一个表的数据失败(ora-01779)常常是这个原因。

linux

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How does MySQL handle data replication?How does MySQL handle data replication?Apr 28, 2025 am 12:25 AM

MySQL processes data replication through three modes: asynchronous, semi-synchronous and group replication. 1) Asynchronous replication performance is high but data may be lost. 2) Semi-synchronous replication improves data security but increases latency. 3) Group replication supports multi-master replication and failover, suitable for high availability requirements.

How can you use the EXPLAIN statement to analyze query performance?How can you use the EXPLAIN statement to analyze query performance?Apr 28, 2025 am 12:24 AM

The EXPLAIN statement can be used to analyze and improve SQL query performance. 1. Execute the EXPLAIN statement to view the query plan. 2. Analyze the output results, pay attention to access type, index usage and JOIN order. 3. Create or adjust indexes based on the analysis results, optimize JOIN operations, and avoid full table scanning to improve query efficiency.

How do you back up and restore a MySQL database?How do you back up and restore a MySQL database?Apr 28, 2025 am 12:23 AM

Using mysqldump for logical backup and MySQLEnterpriseBackup for hot backup are effective ways to back up MySQL databases. 1. Use mysqldump to back up the database: mysqldump-uroot-pmydatabase>mydatabase_backup.sql. 2. Use MySQLEnterpriseBackup for hot backup: mysqlbackup--user=root-password=password--backup-dir=/path/to/backupbackup. When recovering, use the corresponding life

What are some common causes of slow queries in MySQL?What are some common causes of slow queries in MySQL?Apr 28, 2025 am 12:18 AM

The main reasons for slow MySQL query include missing or improper use of indexes, query complexity, excessive data volume and insufficient hardware resources. Optimization suggestions include: 1. Create appropriate indexes; 2. Optimize query statements; 3. Use table partitioning technology; 4. Appropriately upgrade hardware.

What are views in MySQL?What are views in MySQL?Apr 28, 2025 am 12:04 AM

MySQL view is a virtual table based on SQL query results and does not store data. 1) Views simplify complex queries, 2) Enhance data security, and 3) Maintain data consistency. Views are stored queries in databases that can be used like tables, but data is generated dynamically.

What are the differences in syntax between MySQL and other SQL dialects?What are the differences in syntax between MySQL and other SQL dialects?Apr 27, 2025 am 12:26 AM

MySQLdiffersfromotherSQLdialectsinsyntaxforLIMIT,auto-increment,stringcomparison,subqueries,andperformanceanalysis.1)MySQLusesLIMIT,whileSQLServerusesTOPandOracleusesROWNUM.2)MySQL'sAUTO_INCREMENTcontrastswithPostgreSQL'sSERIALandOracle'ssequenceandt

What is MySQL partitioning?What is MySQL partitioning?Apr 27, 2025 am 12:23 AM

MySQL partitioning improves performance and simplifies maintenance. 1) Divide large tables into small pieces by specific criteria (such as date ranges), 2) physically divide data into independent files, 3) MySQL can focus on related partitions when querying, 4) Query optimizer can skip unrelated partitions, 5) Choosing the right partition strategy and maintaining it regularly is key.

How do you grant and revoke privileges in MySQL?How do you grant and revoke privileges in MySQL?Apr 27, 2025 am 12:21 AM

How to grant and revoke permissions in MySQL? 1. Use the GRANT statement to grant permissions, such as GRANTALLPRIVILEGESONdatabase_name.TO'username'@'host'; 2. Use the REVOKE statement to revoke permissions, such as REVOKEALLPRIVILEGESONdatabase_name.FROM'username'@'host' to ensure timely communication of permission changes.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

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

Hot Tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

mPDF

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),

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment