At 16:48 -0600 3/7/02, Kenneth Hylton wrote: >Howdy - >I've posted this twice before - third time might be the charmer... >Can anybody help me? >I am using the C API and am returning a result set from a table with a BLOB >type item in it. >When I populate the BLOB fields initially (with all the same data) the >length is returned properly when I issue SELECT * FROM <table> and decode >the result set column metadata. >Meaning, that if I put , "This Blob's for you!" in the column, the value of >MYSQL_FIELDS.length = 65535 (max of BLOB type) and MYSQL_FIELDS.max_length = >21. >When I update a few rows and put, "That's OK man, but you still can't have >my BLOB!" in a few columns, the values for the length of the fields are >returned funny, or at least, I don't understand why they are returning they >way they are. >Meaning the value of the new column length are all set to >MYSQL_FIELDS.length = 65535 (again, max of BLOB type) and >MYSQL_FIELDS.max_length = 49. Problem is, this is even on the unchaged >rows! Yuk! >A little experimentation showed that if I select on only unchanged rows, the >length is returned as 21. But, if the result set has one of the changed >rows in it, the length of all blob fields is returned as 49, when (at least >to me) it should be 21 or 49. >In other words, it returns as the BLOB max_length value the value of the >longest blob in the result set, NOT the max_length of each row. I inserted
Right. That's how it's supposed to work. length = length of the underlying column type, as defined in the CREATE TABLE statement. max_length = length of the longest value actually present in the result set. Neither of them indicate anything about particular values present in a given row. If you want that, use mysql_fetch_lengths() to get a pointer to an array of the lengths of the columns in the current row of the result set. >(and updated) some records in the table with BLOB contents "It's all about >the BLOB" and I see the same result. It returns not the length of the BLOB >for the row, but the length of the longest BLOB field in the result set. >We are running MySQL 3.23.46-Max on RedHat 7.2 Question: >1) How do I get the actual length of the BLOB column in the row, >without storing a separate column to maintain BLOB length manually? >2) If this is not a problem because there is some other way to tell >where the BLOB buffer ends, please let me know. --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
