How to convert data from GB2312 to UTF-8

How to convert data from GB2312 to UTF-8
I used the iconv and mb_convert_encoding two functions have tried, and then found that the results are the same, there will be a variety of problems, not where the word is a direct error, ask God how to solve AH
------Solution--------------------
GBK data is inserted into the UTF8 table, only one mysql_query (' Set names GBK ') is executed once before insertion; You can do it.

mysql_query (' set names GBK');
The purpose of this instruction is to notify MySQL to now operate with the GBK character set
transcoding work done by MySQL yourself

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