mysql表创建新行而不是更新

Question

Instead of finding that a row exists where 'bookName' equals 'bookName' and just updating, it creates a brand new row. What is wrong with my command? thanks!

$query = mysql_query(
"INSERT INTO custombookinfo (userId, sendToAddress, work, caseStudies, url, entryPoint, date, bookName) 
 VALUES ('$userId', '$emailAddress', '$work', '$caseStudies', '$url', '$entryPoint', '$date', '$bookName') 
 ON DUPLICATE KEY UPDATE bookName = 'bookName'"
);

Answer 1

the INSERT query is correct but I think you have failed to define UNIQUE constraint on column bookName. Execute the following statement:

ALTER TABLE custombookinfo ADD CONSTRAINT tb_uq UNIQUE (bookName);