问题
I'm experiencing a weird hex string result when trying to concat a string with a column that should be of LONGTEXT type.
The query goes like this:
SELECT concat("abc",t.LONGTEXT_VALUE,"cde") FROM mytable t
61626354657374696e67636465
The hex string 61626354657374696e67636465 is the correct value, just in hexadecimal form.
A SELECT on the column itself will return the normal string:
SELECT t.LONGTEXT_VALUE FROM mytable t
Testing
回答1:
Have you tried casting? Usually works pretty well for me. Example:
SELECT CONCAT("abc",CAST(t.LONGTEXT_VALUE AS CHAR),"cde") FROM mytable t
回答2:
When you concat a number without a cast it returns as a blob. This is intended functionality of MySQL as far as I can tell since, it was reported in this bug thread and they closed it and confirmed it was returning a Blob.
来源：https://stackoverflow.com/questions/18840557/mysql-concatstring-longtext-results-in-hex-string