msg d'erreur : "Incorrect usage of UPDATE and LIMIT"

2 tables :

- T1 :
id - int
x - boolean

- T2 :
ref - int
x - boolean

Une requête :
update T1 left join T2 on T2.ref=T1.id set T1.x=true where (T2.x=true or isnull(T2.x)) limit 1;

Et le message d'erreur "Incorrect usage of UPDATE and LIMIT"

Pas d'erreur sans LIMIT 1
Avez-vous une idée ?

Bonjour,

Extraits de la page UPDATE du manuel MySQL :

Citation:

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For the multiple-table syntax, UPDATE updates rows in each table named in table_references that satisfy the conditions. In this case, ORDER BY and LIMIT cannot be used.

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Citation:

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You can also perform UPDATE operations covering multiple tables. However, you cannot use ORDER BY or LIMIT with a multiple-table UPDATE

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http://dev.mysql.com/doc/refman/5.0/en/update.html