thinkphp the differences between the instantiated objects m () and D ()

What is the difference between instantiating objects m () and D () in thinkphp? thinkphp How do I instantiate an object?
In the process of instantiation, the D method and M method are often used, the difference between the two methods is that the M method instantiation model does not require the user to define a model class for each data table, and the M method is automatically called if the D method does not find a defined model class.
Popular Point says:
The M instantiation parameter is the table name of the database.
D instantiates the model file you created underneath the Model folder.

For example: $user = Newusermodel ();equivalent to $user =d (' user ');If an empty model is instantiatedfor example $Demo = Newmodel ();then it is equivalent to $Demo =m ();

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the difference between D and M is mainly:
The M method does not need to create a model class file, and the M method does not read the model class, so automatic validation is not valid by default, but can be achieved by dynamically assigning values
The D method must have a model class created.

We can use the following two ways to create a mapping object for a data table
First type: $Test = D (' Test ')
Second type: $Test = new Model (' Test ')
Although both of these can be select,insert,delete,udpate operations on the data,
Data validation is very different, in the first instance a model will have a data check function, if the title is not filled in the words will prompt "Please enter the title" (This is a TP provides an automatic verification function, of course, also need to define the corresponding model in the validation conditions);

If we use the second kind, there's no.

There are 1 differences when using the $truetablename, you must use the $test=d (' test '), indicating that the query is the test table,

If you are using $test=m (' test '), it means that the data side of the query is think_test.

thinkphp2.0 version test has such a problem as above
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Popular Point says:
D is to instantiate a model based on the model file.
M is dynamically instantiating a model object by directly instantiating the model method (thinkphp base class), even if the corresponding model file does not exist
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A quick instantiation of the Action class library
B Execution Behavior Class
C Configuration Parameter access method
D Fast instantiation of the Model class library
F Fast and simple text data access method
L Language Parameter access method
M fast High performance instantiation model
R quickly remotely invoke the Action class method
s Fast Cache access method
U URL dynamic Generation and redirection method
W Fast Widget Output method

The D function instantiates the module below the Lib/model of your current project.
If the module does not exist, return the object that instantiates the model directly (meaning is the same as the M () function).
and M only returns, instantiating the model object. Its $name parameter handles the operation of the database as a table name for the database.

thinkphp the differences between the instantiated objects m () and D ()