how to create trigger

MySQL database trigger) MySQL trigger: monitors a situation and triggers an operation I. Four Elements Trigger time: before/after Location: table Monitoring Operation: insert/update/delete Trigger operation: insert/update/delete   Ii. Create a

From:http://www.cnblogs.com/hoojo/archive/2011/07/20/2111316.htmlA trigger is a special type of stored procedure that differs from the stored procedure we described earlier. Triggers are triggered primarily by an event that is automatically invoked

SQL Server triggers enable simultaneous addition, deletion, and update of multiple tables Definition: What is a trigger? In SQL Server is a certain operation of a table, triggering certain conditions, thus executing a program. A trigger is a

1. Why use triggers: In a MySQL database, a Database object table is a logical structure for storing and manipulating data, and database object triggers are used to implement an action that is triggered by some table events. In a database system,

1. For the above Salaries table emp_no field to create an index idx_emp_no, query emp_no for 10005, The topic description creates an index idx_emp_no for the Salaries Table emp_no field, and the query emp_no to 10005, using the mandatory

The examples in this article describe Oracle trigger usage. Share to everyone for your reference, as follows: First, Trigger introduction trigger definition When a condition is set up, the statements defined in the trigger are automatically executed.

Q: What is a trigger?A:A trigger is a database object that is related to a table, fires when a condition is met, and executes a collection of statements defined in the trigger.650) this.width=650; "Src=" http://images2015.cnblogs.com/blog/1113510/201

1. A simple example1.1. Create a table:CREATE TABLE T (S1 integer);1.2. Trigger: delimiter | create  trigger   t_trigger before insert  on   t  for  each row begin  set  @x = "Hello trigger" set  new.s1 =; end |

MySQL trigger syntax specific explanation:trigger trigger is a special kind of stored procedure . He triggers a run when inserting (inset), deleting (delete), or altering (update) data in a particular table , which is more granular and more complex

4 Correlation query ( Multi-table Query ) --************** second, related query (multi-table query)****************------ demand: Query employees and their departments ( Show employee name, department name )--2.1 Cross connect query

MySQL database Advanced (v)--trigger one, Introduction to triggers 1, Introduction to TriggersA trigger is a special stored procedure associated with a table that triggers execution when data is inserted, deleted, or modified in a table, with finer

cve-2012-5613 is a vulnerability where file permissions write trigger TRG store files (that is, forged trigger), which are triggered by root to elevate privilege. Do not know why this loophole has not been repaired, probably MySQL think this is a

junction tableCreate a junction from table 1, table 2 is similar to the inner join; if you lose the WHERE clause, a Cartesian product appearsInner Junction INNER JoinAdvanced JunctionSelf-junction example: Select field B from table where field a =

Database Review ⑧June 18, 201621:23Main Integrity Constraints Entity integrity constraints1. various constraintsKeysForeign-key FOREIGN KEY referential integrity constraintsvalue-based Constraints Value Constrainttuple-based Constraints tuple

The pre-update and updated values are often used in triggers in the database, and it is important to understand the role of new and old. I had a situation like this: I was going to insert a row of data, get a unit price in the other table, and then

The concept of a trigger: It is event-driven, like a listener in Java, and when an event occurs, it does some work.Following the dry goods directly, create an INSERT trigger, a DELETE trigger, a DDL trigger, and how to view the trigger definition1.

Trigger:a special kind of thing. You can monitor a data operation and trigger related actions (Insert/update/delete). some of the data in the table change, hoping that the same time can cause other related data changes in demand. Role: Change their

1. Curriculum ReviewMySQL Basics1) MySQL storage structure: Data SQL statements, tables, database2) Management database:Add: Create database default character UTF8;Delete: Drop database;Modified: ALTER DATABASE default character GBK;Query: Show

outfile exporting data from a databaseSELECT * into outfile ' e://mysqloutfile//1.txt ' from table name;Backup and restoreNo longer backup in MySQL directory, mysqldump-uroot-p database name + table name > Specific path name (where do you want to

1. A simple example1.1. Create a table:CREATE TABLE T (S1 integer);1.2. Trigger: delimiter | create  trigger   t_trigger before insert  on   t  for  each row begin  set  @x = "Hello trigger" set  new.s1 =; end |