Is this good for three nights - JSON&PHP, _PHP tutorial-PHP Tutorial-php.cn

Is this good for three nights - JSON&PHP, _PHP tutorial

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Release： 2016-07-12 09:04:17

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How about high for three nights - JSON&PHP,

I went to eat hot pot last night, yes, you guessed it right, I am in Chengdu

My seniors are treating me tonight, and my gay friends are treating me to hotpot tomorrow. I am supposed to be busy this week and have to be high three nights in a row (single graduate students are so easily satisfied). So I have no choice but to stop doing my job and write and write (I can’t write anymore...)

1. JSON

-----Introduction-----

Javascript Object Notation, a lightweight data exchange format

---

Basic Grammar: Four Basic Rules

Parallel data are separated by commas; mapping is represented by colon; collections (arrays) of parallel data are represented by []; mapped collections (objects) are represented by {}

For example: Beijing has an area of 16,800 square kilometers and a permanent population of 16 million; Shanghai has an area of 6,400 square kilometers and a permanent population of 18 million

expressed in JSON format is:

[

{"City":"Beijing","Area":16800,"Population":1600},

{"City":"Shanghai","Area":6400,"Population":1800}

]

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Advantages: Simple format, easy to read, write and transmit; supports multiple languages

Disadvantages: The character set must be Unicode; the syntax is too strict

2. PHP&MySQL

-----php built-in mysql function (2)-----

----Four fetch functions_get the results

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$query=mysqli_query($con, 'select * from test');

print_r(mysqli_fetch_row($query));

The first fetch, mysql_fetch_row(), only returns the data of the first row; Note that it actually reads one row at a time, row by row, so it can all be output like this:

$query=mysqli_query($con, 'select * from test');
while($row=mysqli_fetch_row($query)){
print_r($row);
}

Moreover, if the number of calls is greater than the number of rows, data exceeding the number of rows will not be output and null will be returned

Array ( [0] => 1 [1] => Tom ) Array ( [0] => 2 [1] => Tom ) Array ( [0] => 3 [ 1] => Tom ) Array ( [0] => 4 [1] => Tom ) Array ( [0] => 5 [1] => ???? ) Array ( [0] = > 6 [1] => Tom ) Array ( [0] => 7 [1] => ???? )

You can see that the returned result is an index array

---

mysql_fetch_array()

$arr=mysqli_fetch_array($query);
print_r($arr);

Usage is similar, result:

Array ( [0] => 1 [id] => 1 [1] => Tom [name] => Tom )

Compare database data

mysql> SELECT * FROM TEST;
---- ------
| id | name |
---- ------
| 1 | Tom |
| 2 | Tom |
| 3 | Tom |
| 4 | Tom |
| 5 | ???? |
| 6 | Tom |
| 7 | ???? |
---- ------

So, row takes a piece of data to generate an index array; array defaults to taking a piece of data to generate an index array and an associative array

To put it simply, array can use key names, which is quite convenient:

echo $arr['name'];

But array is a little slower

At the same time, array also has an optional second parameter, you can choose which array/arrays to output

$arr=mysqli_fetch_array($query,MYSQL_ASSOC);
print_r($arr);
echo $arr['name'];

Get

Array ( [id] => 1 [name] => Tom ) Tom

MYSQL_ASSOC, MYSQL_NUM, MYSQL_BOTH are just three parameters

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mysql_fetch_assoc()

Basically the same thing as in the previous section, the output is the same

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