Explanation of the differences between instance Model methods in ThinkPHP_PHP Tutorial

In TP, we can use the following two methods to create a mapping object of a data table (what I use temporarily)
The first method: $Test = D('Test')
The second method: $ Test = new Model('Test')
Although both can perform select, insert, delete, and udpate operations on data, they are very different in data verification.
Let’s take a look at the effect. First Create a TestModel

Create a TestAction

When running, you will find that using the first method to instantiate a model will have a data check function. If the title is not filled in, it will prompt "Please enter a title. ” (This is an automatic verification function provided by tp. Of course, the verification conditions need to be defined in the corresponding model); if you use the second method, it will not be available...