* How to import mysql data to Core Data:
1.  run mysql service (it's XAMPP in my case)
2.  open Terminal, go to "/Users/Perry/projects/WordTotalFrequency2/WordTotalFrequency/Data Importer"
3.  run command: "./mysql2sqlite.sh -u root wtf_cn | sqlite3 mysql.sqlite"
    (note: if exception thrown, check if mysql.sqlite exists under Data Importer, delete it if it exists)
4.  run command: "python sqlite2coredata.py"

* How to include mp3 in build?
1. uncomment lines 203-209 in WordDetailView.m
2. goto project build settings -> EXCLUDED_SOURCE_FILE_NAMES, clear value "*.mp3"
3. clean project by executing "Product->Clean" command
4. build the project

* How to normalize words fields
1. phonetic symbol
    update word set phonetic = CONCAT(phonetic, " ") where locate("/", phonetic)>0
    update word set phonetic = REPLACE(phonetic, "/", "[")
    update word set phonetic = REPLACE(phonetic, "[ ", "] ")
    update word set phonetic = TRIM(phonetic)
2. translate ending
    update word set translate = REPLACE(translate, "；", "") where translate LIKE "%；"
    update word set translate = REPLACE(translate, ";", "") where translate LIKE "%;"
3. detail ending
    update word set detail = REPLACE(detail, "；\n", "\n") 
    update word set detail = REPLACE(detail, ";\n", "\n") 
4. tags
    update word set tags = CONCAT(tags, 'cet4,') where LOCATE('cet4', tags)=0 and spell in (select spell from cet4)