MYSQL触发器的使用_MySQL-Mysql Tutorial-php.cn

Home

Database

Mysql Tutorial

MYSQL触发器的使用_MySQL

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 01, 2016 pm 01:42 PM

updatefor

bitsCN.com
mysql触发器格式为 create trigger trigger_name after/before insert/update/delete on one_table for each row your_sql; 红色部分为自己命名的，蓝色部分为选择一个值，黑色部分必有，最后的绿色部分为你想出发的SQL语句； mysql中关于两个table连接操作update方法为（mysql在此处不使用join语句）： update A,B set A.a2 = B.b2 where A.A1 = B.B1 and B.B2 = "XXX"其中A、B为用户所建立的表名a2、b2为表下的属性值； mysql中使用触发器获得刚刚插入的数据关键字为NEW，即（本人对数据库的命名习惯不好）： table1： records（accountid，date， month， week，income，expend ，remark）； table2： Rweek（ week，Wincome， Wexpend）；触发器为实现table1插入一组数据，table2针对对应的week值进行相应的汇总： create trigger t1 after insert on records for each row update Rweek set Rweek.Wincome=Rweek.Wincome+NEW.income,Rweek.Wexpend=Rweek.Wexpend+NEW.expend where Rweek.week=NEW.week; 作者 Chanthon bitsCN.com

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

MySQL String Types: Storage, Performance, and Best PracticesMay 10, 2025 am 12:02 AM

MySQLstringtypesimpactstorageandperformanceasfollows:1)CHARisfixed-length,alwaysusingthesamestoragespace,whichcanbefasterbutlessspace-efficient.2)VARCHARisvariable-length,morespace-efficientbutpotentiallyslower.3)TEXTisforlargetext,storedoutsiderows,

Understanding MySQL String Types: VARCHAR, TEXT, CHAR, and MoreMay 10, 2025 am 12:02 AM

MySQLstringtypesincludeVARCHAR,TEXT,CHAR,ENUM,andSET.1)VARCHARisversatileforvariable-lengthstringsuptoaspecifiedlimit.2)TEXTisidealforlargetextstoragewithoutadefinedlength.3)CHARisfixed-length,suitableforconsistentdatalikecodes.4)ENUMenforcesdatainte

What are the String Data Types in MySQL?May 10, 2025 am 12:01 AM

MySQLoffersvariousstringdatatypes:1)CHARforfixed-lengthstrings,2)VARCHARforvariable-lengthtext,3)BINARYandVARBINARYforbinarydata,4)BLOBandTEXTforlargedata,and5)ENUMandSETforcontrolledinput.Eachtypehasspecificusesandperformancecharacteristics,sochoose

How to Grant Permissions to New MySQL UsersMay 09, 2025 am 12:16 AM

TograntpermissionstonewMySQLusers,followthesesteps:1)AccessMySQLasauserwithsufficientprivileges,2)CreateanewuserwiththeCREATEUSERcommand,3)UsetheGRANTcommandtospecifypermissionslikeSELECT,INSERT,UPDATE,orALLPRIVILEGESonspecificdatabasesortables,and4)

How to Add Users in MySQL: A Step-by-Step GuideMay 09, 2025 am 12:14 AM

ToaddusersinMySQLeffectivelyandsecurely,followthesesteps:1)UsetheCREATEUSERstatementtoaddanewuser,specifyingthehostandastrongpassword.2)GrantnecessaryprivilegesusingtheGRANTstatement,adheringtotheprincipleofleastprivilege.3)Implementsecuritymeasuresl

MySQL: Adding a new user with complex permissionsMay 09, 2025 am 12:09 AM

ToaddanewuserwithcomplexpermissionsinMySQL,followthesesteps:1)CreatetheuserwithCREATEUSER'newuser'@'localhost'IDENTIFIEDBY'password';.2)Grantreadaccesstoalltablesin'mydatabase'withGRANTSELECTONmydatabase.TO'newuser'@'localhost';.3)Grantwriteaccessto'

MySQL: String Data Types and CollationsMay 09, 2025 am 12:08 AM

The string data types in MySQL include CHAR, VARCHAR, BINARY, VARBINARY, BLOB, and TEXT. The collations determine the comparison and sorting of strings. 1.CHAR is suitable for fixed-length strings, VARCHAR is suitable for variable-length strings. 2.BINARY and VARBINARY are used for binary data, and BLOB and TEXT are used for large object data. 3. Sorting rules such as utf8mb4_unicode_ci ignores upper and lower case and is suitable for user names; utf8mb4_bin is case sensitive and is suitable for fields that require precise comparison.

MySQL: What length should I use for VARCHARs?May 09, 2025 am 12:06 AM

The best MySQLVARCHAR column length selection should be based on data analysis, consider future growth, evaluate performance impacts, and character set requirements. 1) Analyze the data to determine typical lengths; 2) Reserve future expansion space; 3) Pay attention to the impact of large lengths on performance; 4) Consider the impact of character sets on storage. Through these steps, the efficiency and scalability of the database can be optimized.

See all articles