5. Tools used to build software

#### 5.1. PHP5 programming language

PHP (recursive acronym for: PHP5: Hypertext Preprocessor) is a programming language widely used today to generate content for the WEB [17]. PHP was created in 1995 by Rasmus Lerdorf, initially being a CGI package to replace Perl Scripts. PHP initially allowed developers to create simple web applications. Currently available the "PHP 5" version released in 2004, PHP 5 was designed based on Zend Engine 2.0 and brought several innovations. The object orientation of this version of PHP has been fully rewritten to meet the new needs [18].

PHP has source code available for everyone at no cost. The license to use and edit is Open Source, meaning no one can market any modified version of PHP, and any modification must continue with Open Source code for users to explore and modify. This license system does not bring profit to developers because they make everything available to the public for free, and the public, in turn, helps by reporting bugs and helping to modify the source code. Many companies support PHP developers because they do not aim for profit by creating and developing the program. PHP is heavily used with Linux and MySQL, two other Open Source programs [18].

Other advantages of the system are: to be totally free, to work on any operating system in which it is possible to install a web server (multi-platform) and to be able to be easily connected with OpenData Base Connectivity (ODBC) standard systems [19].

Due to its great autonomy, it is a language that allows to create dynamic web sites, allowing a user interaction through forms, URL parameters and links. The difference of PHP with respect to languages similar to Javascript is that the PHP code can be executed on the server, being sent to the client only pure html. In this way, it is possible to interact with existing databases and applications on the server, with the advantage of not exposing the source code to the client. This can be useful when the program is dealing with passwords or any kind of confidential information.

#### 5.2. The MySQL relational database system

Once the result of F2 is obtained, if this result is lower than the recommended amount for the

In a second step, the fertilizers containing potassium (K) are used, such as potassium phosphate monobasic, potassium chloride (white) or potassium sulfate. After choosing the fertilizer, it must be checked if there is potassium leftover from the first calculation, and if this

If there is no "leftover," this formula is used in the same way as previously used, based on the

This is done until all the macronutrients are calculated by calculating the recommended

In a final step of the calculation, not visible to the user, the calculations are made using the micronutrient contents of the fertilizers: boric acid, copper sulfate, manganese sulfate, zinc sulfate, sodium molybdate and ferrous sulfate. To calculate the macronutrients, the formula (1) is used. Finally, the results are converted to the capacity of the chosen tank, and for 1000 L, the results are multiplied by 1, if they are 2000 L, the results are multiplied by 2, so successively up to the

Next, a report is presented, which can be converted to PDF format for print, and the PHP

Fertilizers: option where all the fertilizers used to calculate nutrient solutions are visualized. In the "Help" section, you can find the following options: Tutorial, where you can access a tutorial explaining the steps to create a solution and calculate it and get information to contact

In the current version of the system, there is an administrative area, where it is possible to measure the number of users registered, where the "Administrators" group that associates with the user was added, restricting access to this area only to users belonging to this group. With the option "User Report," the name of the users with a totalizer is listed, leaving the structure open

PHP (recursive acronym for: PHP5: Hypertext Preprocessor) is a programming language widely used today to generate content for the WEB [17]. PHP was created in 1995 by Rasmus Lerdorf, initially being a CGI package to replace Perl Scripts. PHP initially allowed developers to create simple web applications. Currently available the "PHP 5" version released in 2004, PHP 5 was designed based on Zend Engine 2.0 and brought several innovations. The object

orientation of this version of PHP has been fully rewritten to meet the new needs [18].

library, mPDF that converts HTML to PDF, was used for this task. The report contains:

crop, the process will be redone, starting with F1, using another fertilizer.

92 Potassium - Improvement of Quality in Fruits and Vegetables Through Hydroponic Nutrient Management

happens, the following formula should be used:

the system developers, as well as the tools used.

fertilizer chosen.

amounts for each crop.

maximum value of 5000 L.

for more options for this area.

5. Tools used to build software

5.1. PHP5 programming language

MySQL is a relational database management system. A relational database stores data in separate tables instead of putting all the data in one place. This provides speed and flexibility [20].

SQL is the most common default language used for database access and is defined by the ANSI/ ISO SQL standard. The SQL standard has been evolving since 1986, and there are several versions [21].

The MySQL is an Open Source software. Open Source means that it is possible for anyone to use and modify the program. Anyone can download MySQL over the Internet and use it without paying for it [22].

The MySQL database server is extremely fast, reliable, and easy to use. The MySQL Server also has a set of very practical features developed with the cooperation of users [21].

The MySQL Server was originally developed to handle very large databases much faster than existing solutions and has been used successfully in high demand production environments for several years [20].

The MySQL Database Program is a client/server system consisting of a multitasking SQL server that supports different accesses, various client programs and libraries, administrative tools and various programming interfaces [21].

#### 5.3. The cascading style sheets: CSS3

Cascading Style Sheets, or Cascade Style Sheets, are formatting files for HTML documents. Its great advantage is in the association with HTML pages, which greatly facilitates the process of formatting serial pages. For example, suppose there is a site consisting of dozens of pages, and at some point it is necessary to make a change in the formatting, the background, the format of the tables, and so on. With CSS, you can associate all of these pages with a single formatting file, so that by changing the CSS file, all HTML pages associated with it are automatically cascaded, that is, when the browser reads a style sheet format the document in accordance with it [21].

can create a header for the header of a blog, with the title and navigation links, and each post, properly created in a chapter, have a header with the title of the post and the date it was published, for example. This can be very useful for architecting more modular pages and for

Software for Calculation of Nutrient Solution for Fruits and Leafy Vegetables in NFT Hydroponic System

http://dx.doi.org/10.5772/intechopen.72243

95

When accessing the system, the user will be redirected to the calculation screen of the solution (Figure 1), where you can choose the desired solution, and if you do not have any solution created, you can use the standard solution, choose the culture and the quantity of the reservoir

improving the quality and maintainability of developed code [24].

6. Software Hidrosical and Hidrosolun

in which the solution will be diluted, and then click next.

6.1. Operating the Hidrosolun software

Figure 1. Choice of solution, culture and reservoir.

Figure 2. Choice of fertilizer containing nitrate.

The various additions to CSS 3 are extremely useful for replacing various types of images that are used to add colors and shapes to HTML elements, which you could not do with just CSS. In addition to the reduction of files to work and the absence of external dependencies that impact on the performance of the sites, the flexibility of these properties allows several combinations, which generate different styles that offer greater simplicity when creating with CSS only [23].

#### 5.4. The HTML5 markup language

HTML is the abbreviation for Hypertext Markup Language, or Hypertext Markup Language. It is not exactly a programming language, but rather a pattern for representing elements of a web page that can be viewed in a browser program. The HTML code is sent from the server to the client computer, and the client has the task of translating this code into user-readable information [18].

The code of an HTML page consists of tags called tags, which are used to identify elements present on a page, such as text with paragraphs, line breaks, links, images, tables and so on. Each of these elements has a specific tag that identifies it. The tags are represented by the character "<", followed by the specific tag name, plus the ">"character, to start tagging [18].

Example: <Html>. <Head>. <Title> Page title </ title>.

</ Head>.

<Body>.

This is an example page. <B > This text is bold </ b>.

</ Body>.

</ Html>.

With the evolution of technology, new version appeared and was called HTML5 and the emergence of HTML5 has changed many things in the world of web development, with new elements, new features and several other new features that enable better experiences and integrations that were previously only wishes and dreams of the developers. Even with some features still in the process of definition, it is already possible to take advantage of many of the new features that HTML5 has brought to the world [20].

A crucial point of these changes is that one can define several independent sections, each with its own hierarchy. For example, it is possible to have 2 h1 elements, each in its section; or you can create a header for the header of a blog, with the title and navigation links, and each post, properly created in a chapter, have a header with the title of the post and the date it was published, for example. This can be very useful for architecting more modular pages and for improving the quality and maintainability of developed code [24].
