We started to export 10kV Transmission Line Steel Pole to Philippines from 2004 and supply more than 50,000 pcs each year.
Our firm introduced whole set of good-sized numerical control hydraulic
folding equipment(1280/16000) as well as equipped with a series of
good-sized professional equipments of armor plate-flatted machine,
lengthways cut machine, numerical control cut machine, auto-closed up
machine, auto-arc-weld machine, hydraulic redressing straight machine,
etc. The firm produces all sorts of conical, pyramidal, cylindrical
steel poles with production range of dia 50mm-2250mm, thickness
1mm-25mm, once taking shape 16000mm long, and large-scale steel
components. The firm also is equipped with a multicolor-spayed
pipelining. At the meantime, for better service to the clients, our firm
founded a branch com. The Yixing Jinlei Lighting Installation Com,
which offers clients a succession of service from design to manufacture
and fixing.
10kV Steel Pole, Low voltage Steel Power Pole, Steel Power Tubular Pole, Steel Tubular Post JIANGSU XINJINLEI STEEL INDUSTRY CO.,LTD , https://www.steel-pole.com
Mysql trigger simple instance
MySQL, compared to other large databases like Oracle, DB2, and SQL Server, has its own limitations. However, this hasn't diminished its popularity. For individual users and small to medium-sized businesses, MySQL offers more than enough functionality. Additionally, since it is open-source software, it significantly reduces the total cost of ownership.
Linux as the operating system, Apache or Nginx as the web server, MySQL as the database, and PHP/Perl/Python as the server-side scripting language form a powerful and flexible stack. These four components are all free or open-source (FLOSS), allowing you to build a stable, cost-free website system without any upfront expenses—except for labor costs. This combination is commonly referred to as "LAMP" or "LNMP" in the industry.
**MySQL Trigger Example**
A trigger in MySQL is a set of SQL statements that automatically execute in response to certain events on a particular table. Here's a breakdown of how triggers work:
- **Trigger Name**: The trigger must have a name, which can be up to 64 characters long. It follows similar naming conventions as other objects in MySQL.
- **Timing**: The trigger can be set to execute either `BEFORE` or `AFTER` an event (such as an insert, update, or delete).
- **Event Type**: Triggers can be defined to activate on `INSERT`, `UPDATE`, or `DELETE` operations.
- **Table Association**: A trigger is associated with a specific table. It is triggered when an operation is performed on that table.
- **Row-Level Execution**: Using `FOR EACH ROW`, the trigger executes for each affected row, rather than once per statement.
- **SQL Statements**: The body of the trigger contains the SQL statements that will be executed. These can include compound statements, but they are subject to the same restrictions as stored functions.
To create a trigger, you need appropriate privileges, such as `CREATE TRIGGER`. If you're a root user, this should already be available. This differs from the SQL standard.
---
**Example 1: Insert Trigger**
Let’s create two tables, `tab1` and `tab2`, and then define a trigger that inserts a record into `tab2` whenever a new record is added to `tab1`.
```sql
DROP TABLE IF EXISTS tab1;
CREATE TABLE tab1 (
tab1_id VARCHAR(11)
);
DROP TABLE IF EXISTS tab2;
CREATE TABLE tab2 (
tab2_id VARCHAR(11)
);
-- Create a trigger that copies data from tab1 to tab2 after an insert
DROP TRIGGER IF EXISTS t_afterinsert_on_tab1;
CREATE TRIGGER t_afterinsert_on_tab1
AFTER INSERT ON tab1
FOR EACH ROW
BEGIN
INSERT INTO tab2 (tab2_id) VALUES (NEW.tab1_id);
END;
-- Test the trigger
INSERT INTO tab1 (tab1_id) VALUES ('0001');
-- Check results
SELECT * FROM tab1;
SELECT * FROM tab2;
```
**Example 2: Delete Trigger**
Now, let’s create a trigger that deletes a corresponding record from `tab2` whenever a record is deleted from `tab1`.
```sql
DROP TRIGGER IF EXISTS t_afterdelete_on_tab1;
CREATE TRIGGER t_afterdelete_on_tab1
AFTER DELETE ON tab1
FOR EACH ROW
BEGIN
DELETE FROM tab2 WHERE tab2_id = OLD.tab1_id;
END;
-- Test the trigger
DELETE FROM tab1 WHERE tab1_id = '0001';
-- Check results
SELECT * FROM tab1;
SELECT * FROM tab2;
```
These examples demonstrate how MySQL triggers can automate data synchronization between related tables, ensuring consistency and reducing the need for manual intervention. Whether you're building a simple blog or a complex application, understanding triggers can help you manage your database more efficiently.