MySQL error "Specified key was too long; Max key length is 1000 bytes Solution _mysql

After the query to know, is the MySQL field set too long, so I put the length of these two fields changed a bit better.

When an index is indexed, the length of the database calculation key is to accumulate the char length of all the fields used by index and then multiply by the following proportion to no longer than the qualified key length 1000:
Latin1 = 1 byte = 1 character
Uft8 = 3 byte = 1 character
GBK = 2 byte = 1 character
For example to see more clearly, take GBK as an example:
CREATE UNIQUE INDEX ' Unique_record ' on reports (' Report_name ', ' report_client ', ' report_city ');
of which report_name varchar, report_client varchar, report_city varchar (200)
(+200) * 2 = 1200 > 1000, all will report 1071 error, as long as the report_city changed to varchar (100) Then the index can be successfully established.
If the table is a UTF8 character set, the index is still not built.