update from same table in mysql code example

Example 1: update left join mysql

UPDATE  t1
LEFT JOIN
        t2
ON      t2.id = t1.id
SET     t1.col1 = newvalue
WHERE   t2.id IS NULL

Example 2: mysql select update same table

UPDATE
    products_description pd INNER JOIN products_description pd2 ON
    (pd.products_id=pd2.products_id AND pd2.language_id=1 AND pd.language_id<>1)
SET pd.products_seo = pd2.products_seo;