How does dedecms add thumbnails to a channel page?

When a column list uses thumbnails to represent production, it is not just text. Without this function, it will be very troublesome. There are many materials on the Internet for this purpose, however, I have tried a lot of problems. I have studied it myself and basically passed the test. The typeimg field needs to be added.
SQL Execution in the background:

1 alter table '80php _ arctype 'add'typeimg 'char (100) not null default '';

Files involved:
Dede/catalog_add.php
Dede/catalog_edit.php
Dede/templets/catalog_add.htm
Dede/templets/catalog_edit.htm

Open Dede/catalog_add.php
Find $ querytemplate = "insert into '80php _ arctype'
Set

2 (Reid, topid, sortrank, typename, typedir,

Replace

3 (Reid, topid, sortrank, typename, typedir, typeimg,

Set

4 ('~ Reid ~ ','~ Topid ~ ','~ Rank ~ ','~ Typename ~ ','~ Typedir ~ ',

Replace

5 ('~ Reid ~ ','~ Topid ~ ','~ Rank ~ ','~ Typename ~ ','~ Typedir ~ ','~ Typeimg ~ ',

Open Dede/catalog_edit.php
Search

6 $ upquery = "Update '80php _ arctype 'Set

Add a new line under it
'Typeimg '=' $ typeimg ', (14 ohang Mei You Tianjia)

Open Dede/templets/catalog_add.htm
Search

7 <tr>

8 <TD Height = "26"> list naming rules: </TD>

9 <TD>

10 <input name = "namerule2" type = "text" id = "namerule2" value = "{typedir}/list_1_tid1__1_page0000.html" class = "pubinputs" style = "width: 250px "/>

11 </TD>

12 </tr>

Add the following content below
<Tr>
<TD Height = "65" style = "padding-left: 10px;"> topic image: </TD>
<TD>
<Input name = "typeimg" type = "text" style = "width: 250px" id = "typeimg" class = "alltxt" value = ""/>
<Input type = "button" name = "set9" value = "Browse... "Class =" coolbg NP "style =" width: 60px "onclick =" selectimage ('form1. typeimg ', '');"/>
</TD>
</Tr>
Add the following content to the file head:
<Script language = 'javascript 'src = "JS/Main. js"> </SCRIPT>

Open Dede/templets/catalog_edit.htm
Add:
<Tr>
<TD Height = "65" style = "padding-left: 10px;"> topic image: </TD>
<TD>
<Input name = "typeimg" type = "text" style = "width: 250px" id = "typeimg" class = "alltxt" value = "<? PHP echo $ myrow ['typeimg ']?> "/>
<Input type = "button" name = "set9" value = "Browse... "Class =" coolbg NP "style =" width: 60px "onclick =" selectimage ('form1. typeimg ', '');"/>
</TD>
</Tr>
Note: The following statement calls the added path.
<? PHP echo $ myrow ['typeimg ']?>

Add the following content to the file head:
<Script language = 'javascript 'src = "JS/Main. js"> </SCRIPT>

I tried using: {Dede: field. typeimg/} in the template, but no data can be called.

Modify channel. Lib. php

After all $ SQL = "select ID, typename, typedir, isdefault, ispart, defaultname, namerule2, moresite, siteurl, sitepath, and content

Add, typeimg

Similarly, you can add a subtopic title.

How does dedecms add thumbnails to a channel page?