oracle没有date()函数,sysdate函数的值是包括时分秒的,要实现插入当前时间默认值还真麻烦.
Oracle没有date()函数,sysdate函数的值是包括时分秒的,要实现插入当前时间默认值还真麻烦.
只好自己写储存过程,而字段默认值里面又不能调用储存过程,还得写个触发器!而储存过程里面取出来的sysdate前几位的只却变成17-11月-07的格式了,不是自己想要的,2007-11-17的格式,又得单独取年月日再组合起来,这样一来返回值就不能是日期类型而要字符类型了.
一个字,烦!不过还是把他实现了.下面把代码给大家分享一下,如果有更好的方法麻烦告知.
1.储存过程
CREATE OR REPLACE FUNCTION "GET_DATE" RETURN VARCHAR2
IS
yyyy varchar2(36);
mm varchar2(36);
dd varchar2(36);
tempdate varchar2(36);
BEGIN
tempdate := '';
select to_char(to_date(sysdate),'YYYY') into yyyy from dual;
select to_char(to_date(sysdate),'MM') into mm from dual;
select to_char(to_date(sysdate),'DD') into dd from dual;
tempdate := substr(yyyy,1,4)|| '-'||
substr(mm,1,2)|| '-'||
substr(dd,1,2)
;
return tempdate;
END;
2.触发器
CREATE OR REPLACE TRIGGER STATWEEK_tg
--STATWEEK fdate 的触发器
BEFORE INSERT ON STATWEEK FOR EACH ROW
BEGIN
SELECT get_date INTO :NEW.fdate FROM DUAL;
END;
注:这里的STATWEEK为对应的数据表 fdate为自动增长的字段,get_date为对应的储存过程名.
3.数据表
-- Create table
create table STATWEEK
(
星期一 VARCHAR2(20) default 0,
星期二 VARCHAR2(20) default 0,
星期三 VARCHAR2(20) default 0,
星期四 VARCHAR2(20) default 0,
星期五 VARCHAR2(20) default 0,
星期六 VARCHAR2(20) default 0,
星期日 VARCHAR2(20) default 0,
TWEEK VARCHAR2(10),
ADMIN VARCHAR2(50),
FDATE VARCHAR2(20)
)

Stored procedures are precompiled SQL statements in MySQL for improving performance and simplifying complex operations. 1. Improve performance: After the first compilation, subsequent calls do not need to be recompiled. 2. Improve security: Restrict data table access through permission control. 3. Simplify complex operations: combine multiple SQL statements to simplify application layer logic.

The working principle of MySQL query cache is to store the results of SELECT query, and when the same query is executed again, the cached results are directly returned. 1) Query cache improves database reading performance and finds cached results through hash values. 2) Simple configuration, set query_cache_type and query_cache_size in MySQL configuration file. 3) Use the SQL_NO_CACHE keyword to disable the cache of specific queries. 4) In high-frequency update environments, query cache may cause performance bottlenecks and needs to be optimized for use through monitoring and adjustment of parameters.

The reasons why MySQL is widely used in various projects include: 1. High performance and scalability, supporting multiple storage engines; 2. Easy to use and maintain, simple configuration and rich tools; 3. Rich ecosystem, attracting a large number of community and third-party tool support; 4. Cross-platform support, suitable for multiple operating systems.

The steps for upgrading MySQL database include: 1. Backup the database, 2. Stop the current MySQL service, 3. Install the new version of MySQL, 4. Start the new version of MySQL service, 5. Recover the database. Compatibility issues are required during the upgrade process, and advanced tools such as PerconaToolkit can be used for testing and optimization.

MySQL backup policies include logical backup, physical backup, incremental backup, replication-based backup, and cloud backup. 1. Logical backup uses mysqldump to export database structure and data, which is suitable for small databases and version migrations. 2. Physical backups are fast and comprehensive by copying data files, but require database consistency. 3. Incremental backup uses binary logging to record changes, which is suitable for large databases. 4. Replication-based backup reduces the impact on the production system by backing up from the server. 5. Cloud backups such as AmazonRDS provide automation solutions, but costs and control need to be considered. When selecting a policy, database size, downtime tolerance, recovery time, and recovery point goals should be considered.

MySQLclusteringenhancesdatabaserobustnessandscalabilitybydistributingdataacrossmultiplenodes.ItusestheNDBenginefordatareplicationandfaulttolerance,ensuringhighavailability.Setupinvolvesconfiguringmanagement,data,andSQLnodes,withcarefulmonitoringandpe

Optimizing database schema design in MySQL can improve performance through the following steps: 1. Index optimization: Create indexes on common query columns, balancing the overhead of query and inserting updates. 2. Table structure optimization: Reduce data redundancy through normalization or anti-normalization and improve access efficiency. 3. Data type selection: Use appropriate data types, such as INT instead of VARCHAR, to reduce storage space. 4. Partitioning and sub-table: For large data volumes, use partitioning and sub-table to disperse data to improve query and maintenance efficiency.

TooptimizeMySQLperformance,followthesesteps:1)Implementproperindexingtospeedupqueries,2)UseEXPLAINtoanalyzeandoptimizequeryperformance,3)Adjustserverconfigurationsettingslikeinnodb_buffer_pool_sizeandmax_connections,4)Usepartitioningforlargetablestoi


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

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

SublimeText3 Linux new version
SublimeText3 Linux latest version

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

SublimeText3 Chinese version
Chinese version, very easy to use

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.
