According to the W3Cel Document Object Model is an application programming interface (API) for valid HTML and well-constructed XML documents. Defines the logical structure of documents and how they are accessed and manipulated. The DOM allows access to the structure of an HTML page by mapping the elements of this page in a tree of nodes. Each element becomes a node and each piece of text becomes a text node. To understand more easily see the following example:
This is a paragraph that contains <a href=”#”> a link </a> in the middle.
- First item on the list
- Another point on the list
As you can see, an element [a] is located inside an element [p] of the HTML, becoming a child node, or simply a child of node [p], similarly [p] is the parent node. The two nodes li are children of the same parent, called sibling nodes or simply siblings.
It is important to understand the difference between elements and text nodes. Elements are commonly associated with tags. In HTML all tags are elements, such as
, <img> and
so they have attributes and contain child nodes. However, text nodes do not have attributes and children.
Always use the correct DOCTYPE
The DOCTYPE (document type declaration) informs which version of (X) HTML will be used to validate the document; there are several types to select from. The DOCTYPE must always appear at the top of every HTML page and be a key component of standards-compliant web pages.
In case of using an incomplete DOCTYPE, not updated or simply not using it, it will lead the browser to go into weird or strange mode, where the browser assumes that it has been programmed outside of the standards. All current browsers are still not capable of correctly processing all types of documents, however, many of them work correctly in the browsers most used today, such as: HTML 4.01 Strict and Transitional, XHML 1.0 Strict and Transitional behave in the same way. correct mode in Internet Explorer (version 6, 7 Beta), Mozilla and Opera 7. From now on, HTML 4.01 Strict will be adopted for each example: <! DOCTYPE HTML PUBLIC “- // W3C // DTD HTML 4.01 Transitional // EN “” http://www.w3.org/TR/html4/loose.dtd “> Resulting in a single line of code, or two lines with a line break after EN”.
ODBC is a standard access to databases developed by SQL Access Group in 1992, the goal of ODBC is to make it possible to access any data from any application, regardless of what Manager System Database (DBMS for its acronym in English ) store the data, ODBC achieves this by inserting an intermediate layer (CLI) called the SQL Client Interface level, between the application and the DBMS, the purpose of this layer is to translate the application’s data queries into commands that the DBMS in shop. For this to work both the application and the DBMS They must be ODBC compliant, that is, the application must be able to produce ODBC commands and the DBMS must be able to respond to them. Since version 2.0 the standard supports SAG and SQL.
The software works in two ways, with a driver software on the client, or a client-server philosophy. In the first mode, the driver interprets the SQL calls and connections and translates them from the ODBC API to the DBMS. In the second way to connect to the Database, a DSN is created within the ODBC that defines the parameters, path and characteristics of the connection according to the data requested by the manufacturer.
It is a derivative inspired by it, the acronym for Java Database Connectivity, an API that allows the execution of operations on databases from the Java programming language regardless of the operating system where it is executed or the database to which it is run. accessed using the SQL dialect of the database model being used.