Web advanced jQuery operation DOM elements &&MySQL record operation&&PHP object-oriented learning notes, web advanced jquerydom_PHP tutorial

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2. MySQL

-----Records in the operation data table-----

-> id SMALLINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,

-> password VARCHAR(32) NOT NULL,

-> sex BOOLEAN

----Insert record INSERT

INSERT tbl_name [(col_name)] {VALUES|VALUE}...

If a field is omitted, all fields will be assigned values. If you want to keep the primary key incrementing at this time, just write the VALUE of the primary key as NULL/DEFAULT. Moreover, when fields are omitted, values ​​must and can only be assigned to all fields. Each field must be assigned a value. If it does not match, an error will be reported

---- ---------- ----------------------- ----------- ----- ------

---- ------- --- ---------------------------------- ----- ------

| 2 | Tom | 123 | 23 | 1 |

---- --- ------- ---------------------------------- ----- ---- --

----Other methods of inserting records

--INSERT.. SET

The difference from INSERT is that subquery (SubQuery) can be performed; and only one record can be inserted at a time

mysql> SELECT * FROM users;
---- ---------- ----------------------- ----------- ----- ------
| id | username | password | age | sex |
---- ------- --- ---------------------------------- ----- ------
| 1 | Tom | 123 | 28 | 1 |
| 2 | Tom | 123 | 28 | 1 |
| 3 | Rose | 202cb962ac59075b964b07152d234b70 | 15 | 0 |
| 4 | Ben | 323 | 15 | NULL |
---- ---------- -------------------------- ----- ----- ------

Updates all columns at this time.

If you want to update certain columns, you need to use conditions

mysql> UPDATE users SET age=age 10 WHERE id%2=0;

What this means is the operation of adding 10 to the age of an even numbered ID

----Delete records (single table deletion) DELETE

DELETE FROM tbl [WHERE ...]

Pay attention to the change of id after deletion and re-insertion

mysql> DELETE FROM users WHERE id=2;
Query OK, 1 row affected (0.01 sec)

mysql> SELECT * FROM users;
---- ---------- ----------------------- ----------- ----- ------
| id | username | password | age | sex |
---- ------- --- ---------------------------------- ----- ------
| 1 | Tom | 123 | 27 | 0 |
| 3 | Rose | 202cb962ac59075b964b07152d234b70 | 12 | 0 |
| 4 | Ben | 323 | 21 | 0 |
---- --- ------- ---------------------------------- ----- ---- --
3 rows in set (0.00 sec)

mysql> INSERT users SET username='Ben',password='323';
Query OK, 1 row affected (0.01 sec)

mysql> SELECT * FROM users;
---- ---------- ----------------------- ----------- ----- ------
| id | username | password | age | sex |
---- ------- --- ---------------------------------- ----- ------
| 1 | Tom | 123 | 27 | 0 |
| 3 | Rose | 202cb962ac59075b964b07152d234b70 | 12 | 0 |
| 4 | Ben | 323 | 21 | 0 |
| 5 | Ben | 323 | 10 | NULL |
---- ---------- -------------------------- ----- ----- ------

The ID number is automatically added, not filled in intelligently, please note.

----Query SELECT

The most commonly used statements in the database. For example, SELECT * FROM users;

--query expression

Each expression represents a desired column, there must be at least one;

Separate multiple columns with,

* means all columns. tbl_name.* can represent all columns of the named table;

mysql> SELECT id,username FROM users;

You can also change the order to display

mysql> SELECT username,id FROM userS;
---------- ----
| username | id |
---------- ----
| Tom | 1 |
| Rose | 3 |
| Ben | 4 |
| Ben | 5 |
---------- - ---

For the convenience of multi-table query in the future, the "full" query is written like this

mysql> SELECT users.id,users.username FROM users;

--Assign an alias

mysql> SELECT id AS userid,username AS uname FROM users;
-------- -------
| userid | uname |
----- --- -------
| 1 | Tom |
| 3 | Rose |
| 4 | Ben |
| 5 | Ben |
----- --- -------

The names in the data table have not changed

----WHERE condition

Add and delete generally need to be added, otherwise it is an operation on all records; WHERE expressions support functions or operators

----GROUP BY query result grouping

ASC ascending order, DESC descending order

mysql> SELECT sex FROM users GROUP BY sex;
------
| sex |
------
| NULL |
| 0 |
------
2 rows in set (0.01 sec)

mysql> SELECT sex FROM users GROUP BY age ASC;
------
| sex |
------
| NULL |
| 0 |
| 0 |
| 0 |
------

----having grouping conditions

mysql> SELECT sex,age FROM users GROUP BY sex HAVING age>20;
------ -----
| sex | age |
------ -----
| 0 | 27 |
------ -----

Note that the field in the having statement must appear in the select, or simply be an aggregate function (max, etc.)

----Sort query results ORDER BY

Similar to GROUP BY

mysql> SELECT * FROM users ORDER BY age,id DESC;

---- ---------- ---------------------------------- - ----- ------
| id | username | password | age | sex |
---- ---------- ------- -------------------------- ----- ------
| 5 | Ben | 323 | 10 | NULL |
| 3 | Rose | 202cb962ac59075b964b07152d234b70 | 12 | 0 |
| 4 | Ben | 323 | 21 | 0 |
| 1 | Tom | 123 | 27 | 0 |
--- - ---------- ---------------------------------- ----- ------

Note that there is more than one sorting standard here. The default ascending order is based on age. If the same ones are encountered, the same ones are sorted in descending order by id

----LIMIT limits the number of returns

mysql> SELECT * FROM users LIMIT 2,2;
---- ---------- ---------- ----- ---- --
| id | username | password | age | sex |
---- ---------- ---------- ----- -- ----
| 4 | Ben | 323 | 21 | 0 |
| 5 | Ben | 323 | 10 | NULL |
---- ---------- - --------- ----- ------

It should be noted that if you write only one number 2, it means two numbers from the beginning; the 2,2 here means that two numbers will be returned from the third number, because the arrangement starts from 0 by default, so Here is the beginning of Article 3.

In addition, the order of restrictions has nothing to do with ID

mysql> SELECT * FROM users ORDER BY id DESC LIMIT 2;
---- ---------- ---------- ----- -- ----
| id | username | password | age | sex |
---- ---------- ---------- ----- ------
| 5 | Ben | 323 | 10 | NULL |
| 4 | Ben | 323 | 21 | 0 |
---- --------- - ---------- ----- ------

----After learning SELECT

mysql> INSERT test(username) SELECT username FROM users WHERE age>=20;

mysql> SELECT * FROM test;
---- ----------
| id | username |
---- -------- --
| 1 | Tom |
| 2 | Ben |
---- ----------

You can search and write in a targeted manner

----Summary

Record operation: add, update, delete and check

INSERT,UPDATE,DELETE,SELECT

3. Object-oriented

-----Basic Practice-----

----The concept of class

A class can be regarded as a "type of person", with the same "properties" and "methods" (but the corresponding values ​​are not necessarily the same);

Attributes are inherent properties of the class

Methods are the "actions" of the class

The object of the class is called the instantiation of the class - the object is an individual belonging to the class, the concretization of the class

The attributes and methods of a class are class members

----Instantiation of class

Fill the class frame with specific data

/*
* Code for object-oriented learning records
*/
//Definition class
class nbaPlayer{
public $name=" Jordan";
public $height="198cm";
public $team="Bull";

public function __construct(){

}

public function run(){
echo "Runningn";
}
}
//Instantiation
$jordan=new nbaPlayer();
//The calling object’s attributes and Method
echo $jordan->name."n";
$jordan->run();

----Constructor

__construct

Default call, can be customized to give the default value of the class

The method of use is to write the variable in the function and give the value when instantiating it

/*
* Code for object-oriented learning records
*/
//Definition class
class nbaPlayer{
public $name;
public $height;
public $team;

public function __construct($name,$height,$team){
echo "constructingn";//determine whether the constructor is called
$this->name=$name; //Use $this pseudo variable to pass parameters in the method
$this->height=$height;
$this->team=$team ;
}

public function run(){
echo "Runningn";
}
}
//Instantiation
$jordan=new nbaPlayer(" Jordan","198cm","Bull");
//Call the properties and methods of the object
echo $jordan->name."n";

$jordan->run();

$james=new nbaPlayer("James", "197cm", "Heat");

Note that the constructor will be output twice here. In other words, the constructor is called once for each instantiation.

----Destructor

__destruct()

After writing the destructor,

function __destruct(){
echo "destructingn";
}

The results are as follows

constructing Jordan Running constructing destructing destructing

In other words, the destructor will be automatically called when the program ends

Alternatively, the destructor will also be called when the instantiated object is assigned a value of null

Generally used to clean up used resources

----Object reference

//Object reference
$james1=$james;

$james2=&$james;

Among them, there is a reference of &, and the changes of the two objects are synchronized and can be regarded as a kind of image. Specifically, you can use the destructor mentioned above to simply verify.