mysql - php+mysqlupdate

Answer

-- 1 a 1 1 b 2 1 c 3 1 d 4|||while($row1 = mysql_fetch_array($result,MYSQL_ASSOC)) $dbh->exec("update tablename set seq = seq-1 where id = $row1['id'] and seq > 1 ");

Answer

Solution:

I don't know if I understood your problem right, but if this while statement:

while($row1 = mysql_fetch_array($result,MYSQL_ASSOC))
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Loops through rows "b", "c" and "d", the problem is that, with the first loop, the values of "seq" for b, c and d are 1, 2, 3, and then in the second loop, the values of sec for b, c, and d would be 1, 1 and to. Maybe it's the problem. I think what you should do is: 1) Delete the first row 2) Execute the query just once

$dbh->exec("update tablename set seq = seq-1 where id  = $row1['id'] and seq > 1 ");
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You could take the id from the deleted row. Besides, just to make sure everything works, you should add an order by statement to your query:

$dbh->exec("UPDATE tablename SET seq = seq-1 WHERE id = $row1['id'] AND seq > 1 ORDER BY seq ASC ");
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I hope it helps!

Answer

Solution:

because you set primary key (id,seq) together. and basic property of primary key is that..it would be unique and not NULL. so uniqueness of the combination of id and seq must be violated thats why u r getting below error.

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