PHP中的SQL语句错误，但SQL中的错误

Question

The following SQL statement runs correctly against a MySQL database table in an SQL script or in phpmyadmin but errors when run from within a PHP script.

The SQL statement is:

update traceability t1 inner join traceability t2 on (t1.parent in (select t2.child)) set t1.root=false;

in the PHP script the code looks like:

$sqlupdatestmt = $db->query("update traceability t1 inner join traceability t2 on (t1.parent in (select t2.child)) set t1.root=false;");
$sqlupdatestmt->execute();

The error in the PHP log is:

PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[42S22]: Column not found: 1054 Unknown column 't2.child' in 'field list'' in /<myfilepath> /traceability.php:50
Stack trace:
#0 /<myfilepath>/traceability.php(50): PDO->query('update traceabi...')
#1 {main}

What's going wrong in the PHP that it throws a PHP/SQL error?

Here is information on traceability table schema:

Field       Type        Null    Key     Default     Extra   
Variant     varchar(20) YES     MUL     NULL    
Parent      varchar(50) YES             NULL    
Child       varchar(50) YES             NULL    
Relation    varchar(20) YES             NULL    
Root        tinyint(1)  YES             NULL    
Leaf        tinyint(1)  YES             NULL

Answer 1

Try

UPDATE traceability AS t1 set t1.root=false WHERE t1.parent IN (SELECT child FROM traceability)

Anas

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