Heck, it really is baffled, is it a bug? What to do with it

Heck,, really is baffled, is it a bug???
A paragraph of statements

$str = '

123

';

In the Pro Insert database when I print out, watch the source code is like this,

It's weird.

After the database is saved, the source code actually becomes

<pre> 123</pre>

And the database is the same, it is really scary ....

The bug??

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I can print out the SQL statements.
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OK, look at this line of output in the browser source code.

 also not converted? 
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 To see if the database data is healthy. 
 Abnormal check: 
 Echo $sql After insert was not manifested. 
 
 Normal: 
 is the manifested output. 
------Solution--------------------
 Escape character. The 
 
 uses the Addslashes function to insert data into the database and, when read, to revert to normal data using the Stripslashes function. 
------Solution--------------------
 TP Inbound is automatically processed 
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 agreed upstairs to prevent SQL injection attacks. The last addition of that escape is useless. But it seems that the label "<" and ">" (. <pre>) replaced by "&\lt", "&\GT". This allows the code to be displayed correctly, without the code being executed 
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 You use thinkphp, the thinkphp inserts all convert the label to 
 