how to create trigger

MySQL 5.1 includes support for triggers. A trigger is a database object associated with a table operation that is called when a specified event occurs on the table on which the trigger is located . , that is, the execution of a trigger on a table's

MySQL Trigger Basics:Triggers, as the name implies, perform an action based on the triggering or execution of a specific DML statement. MySQL triggers are defined at 6 different integration points:Before insert: Executing a trigger before

--Using regular expressions--^ Start,. Any characterSELECT name, continent, Population from country WHERE Name REGEXP ' ^. [a-e].* ' ORDER by Name;--$ endSELECT name, continent, Population from country WHERE name REGEXP '. *g$ ' ORDER by Name;SELECT

MySQL5.6 Online DDL Unlocked table (add field online)Answer you have a lookMySQL5.6 Online DDL does not lock the table, now I have a 100 million table, need to add a field, if I let you go to increase this field, you should pay attention to what,

The following shows how to implement MySQL data table update real-time trigger SQL Server inside the corresponding table to add and delete operations, first, increase the original MySQL table trigger, including the following three:Inserting data:

One, storageRunning in the MyDB databaseSelect* fromFruitSelect* fromLoginSelect* fromOrderDetailsSelect* fromOrdersSelect* fromInfoSelect* fromFamilygo--stored procedures that enable users to purchase fruit operations, to determine the relationship

via MySQL the UDFs and Trigger Operation MemcachedUDFs is the abbreviation for user Defined functions, which represents a mysql-defined function that the application can use to access the data memcached writes or obtains from a MySQL version of 5.0

I. What trigger is a special stored procedure. Its execution is not called by a program or started manually, but triggered by an event, for example, when you perform operations (insert, delete, update) on a table, it is activated for execution.

1.SQLiteAndroid built-in SQLite database, which is a lightweight embedded database, created by default for each appDatabase is private, its name is unique, and the individual apps cannot access the other's database. Generated by each applicationThe

Using MySQL UDFs and Trigger to operate MemcachedUDFs is short for UserDefinedFunctions, indicating MySQL user-defined functions, applications can use these functions to access data written or obtained by Memcached from databases of MySQL or later

Trigger permission and ownership By default, the create trigger permission is granted to the table owner, sysadmin fixed server role members, db_owner, and db_ddladmin fixed database role members who define the TRIGGER, and cannot be

When data is imported, there are updates. If no data is inserted, there is no CREATE? Trigger? Tr_bank3? ON? Bank3AFTER? INSERTAS ?????? Update? Bank1? Set? Bank1.fmoneybank1. fmoney + c. ??????? From ????????? (Select? Fid, sum (case? When? TYPE0?

Each user can log on to the system, and the operation data (ADD, update, and delete) in the program must be recorded for operation tracking. Who added, updated, and deleted the information, which will be inserted into the AuditLog table. Each user

In SQL, a noun trigger is the program code automatically executed in the database to respond to certain events in a special table. (Wikipedia) is a piece of code that is automatically activated when a special database event, such as INSERT or DELETE

I. Create a database, create tables, and add constraints. 1.1 database creationCopy codeThe Code is as follows:Use masterGoIf exists (select * from sysdatabases where name = 'mydatabas')-determine whether the database name to be created exists in

Copy codeThe Code is as follows:-- Basic SQL operations -- Create a database Create database Studets -- Create a table Create table student (sno char (5), sname char (20), ssex char (2), sage smallint, sdept char (15 )) Create table course (cno char

Sometimes we want data in some tables not to be deleted. We can use the following trigger. Createtrigger [dbo]. [trg_del] on [dbo]. LogInfoinsteadofdeleteASBEGINdeclare @ couintselect @ coucount (*) fromdeleted; if (@ cou0) RAISERROR (data cannot be

On the e-commerce platform, we sometimes need to perform some aggregation calculations on user orders, such as the total number of orders, the total amount, and the average price, there are several methods to achieve this feature: 1. Execute the sum,

Table creation: Create Table [dB. DBO]. tablename (Stud_id int constraint constraintname1 not null primary key, Name nvarchar (5) not null, Birthday datetime, Gender nchar (1 ), Telcode char (12 ), Zipcode char (6) constraint

1. Basic syntax of the trigger:   Create trigger {before | after} {insert | update | Delete} on {table name} for each Row   First, we understand that the trigger belongs to a table. The operation is caused by the insertion, deletion, and