Which datatype to use for specific inserts

Question

I have a array containing some elements:

array(1) { ["dump"]=> string(21) "["0.0",1.1,2.2,99.99]" } 

I need to insert them into in my table, but I don't know which datatype to use.

define('SECURE', true);
require "connect_to_mysql.php";  
$sqlCommand = "CREATE TABLE example (
                 id int(11) NOT NULL auto_increment,
                 inserts float(5),
                 PRIMARY KEY (id),
                 UNIQUE KEY user_name (inserts))";
if ($mysqli->query($sqlCommand)) { 
    echo "Your example table has been created successfully!"; 
} else { 
    echo "CRITICAL ERROR;".$mysqli->error; 
}

Moreover, each array element should be in a separate data field. How do I do that?

UPDATE

var_dump($_POST);   // gives: array(1) { ["dump"]=> string(17) "[3.3,4.3,3.4,4.4]" }
$var["dump"] = $_POST;

$arr = json_decode($var["dump"], true);

$col1 = $arr[0];
$col2 = $arr[1];
$col3 = $arr[2];
$col4 = $arr[3]; 

what i need to do: 1. Count elements, in this case: 4. 2. save every element in a seperate variable. 3. insert those element´s in my table

jsen_encode just returns error in this case

Answer 1

you should use following command to create table

$sqlCommand = "CREATE TABLE example (
             id int(11) NOT NULL auto_increment,
             inserts1 float(5,2),inserts2 float(5,2),
             inserts3 float(5,2),inserts4 float(5,2),
             PRIMARY KEY (id),
                )";

Answer 2

your variable is just single string. you need to split it to 4 variables. the easiest way to do is use json_decode() in your variable format. also as @alok.kumar said. you need 4 columns (I think NUMERIC is better than FLOAT )

this is sample code:

$arr = json_decode($_POST["dump"], true); <= UPDATED

$col1 = $arr[0];
$col2 = $arr[1];
$col3 = $arr[2];
$col4 = $arr[3];

To normalize as other says, you need two tables. following is just example.

Table Schema:

CREATE TABLE example(
  id INT NOT NULL auto_increment,
  primary key(id)
);

CREATE TABLE dumps(
  id INT NOT NULL auto_increment,
  example_id INT NOT NULL,
  dump_value NUMERIC(5,2),
  PRIMARY KEY(id),
  INDEX(example_id),
);

Insert through $_POST ed data:

$arr = json_decode($_POST["dump"], true);

for ($cnt = 0; $cnt < count($arr); ++cnt)
{
    $insert_query = "INSERT INTO dumps (dump_values) VALUES(".$arr[$cnt].")";
}

Answer 3

There are many possible approaches you can go ahead with.Let me list out some of the common approaches

1. Normalizing the data: This means you will have two tables one for saving the primary key and the second table to hold id to each element in array as a row. Pro : Data is better structured, better search of element Con : Logical Validation of data is harder to achieve ( as your combination of insert array is unique)

2. Serializing of insert : You can make you of serialize and unserialize function in php. So you can still get the data in db which will maintain datatype Pro : Well fits in php envirnment and maintains data type Con : Search will be slow as indexing wont work here. Not suited in places where data is is read from other languages like Java

3. JSON encoding: This is current trend, using json encoded text in DB if you dont not have a search option. json is well encoded by most of the languages and is compact. Pro : You can encode and decode in most langauge Con : Search is slow as indexing wont help.

Its based on your requirement and platform you need evaluate and decide on a format. var_dump is not something I would suggest anyways