An explanation of SQL Alias ​​(alias) in php

SQL Alias

SQL Alias ​​syntax for tables

SELECT column_name(s)
FROM table_name
AS alias_name

SQL Alias ​​syntax for columns

SELECT column_name AS alias_name
FROM table_name

Alias ​​Example: Using table name alias

Suppose we There are two tables: "Persons" and "Product_Orders". We give them the aliases "p" and "po" respectively.

Now, we want to list all orders for "John Adams".

We can use the following SELECT statement:

SELECT po.OrderID, p.LastName, p.FirstName
FROM Persons AS p, Product_Orders AS poWHERE p.LastName='Adams' AND p.FirstName='John'

SELECT statement without alias:

SELECT Product_Orders.OrderID, Persons.LastName, Persons.FirstName
FROM Persons, Product_Orders
WHERE Persons.LastName='Adams' AND Persons.FirstName='John'

As you can see from the above two SELECT statements, the alias is queryThe program is easier to read and write.

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