android 数据库升级（保留原先数据）

db.execSQL("CREATE TABLE " + "'post2' (" + //post2 为暂存文件名，可以在这里添加字段或者删除字段
"'_id' INTEGER PRIMARY KEY ," +
"'SONG_ID' INTEGER UNIQUE ," +
"'SONG_NAME' TEXT," +
"'LISTEN_FILE' TEXT," +
"'ARTIST_NAME' TEXT," +
"'HAS_PLAYED' INTEGER  ," +
"'ARTIST_URL' TEXT," +
"'IS_SLOW_TYPE' INTEGER," +
"'SONG_TIME' INTEGER ," +
"'IS_MUSIC_POWER' INTEGER ," +
"'HAS_COLLECTED' INTEGER);");

／／将原先ＬＯＡＤＥＤ＿ＳＯＮＧ　表中中的响应字段的数据ｃｏｐｙ到ｐｏｓｔ２表中
db.execSQL("INSERT INTO post2 (_id, SONG_ID, SONG_NAME, LISTEN_FILE, ARTIST_NAME,  HAS_PLAYED, ARTIST_URL,IS_SLOW_TYPE, SONG_TIME, IS_MUSIC_POWER,HAS_COLLECTED)" +
"   SELECT _id, SONG_ID, SONG_NAME, LISTEN_FILE, ARTIST_NAME,HAS_PLAYED, ARTIST_URL, IS_SLOW_TYPE, SONG_TIME, IS_MUSIC_POWER ,HAS_COLLECTED FROM LOADED_SONG;");
／／删除原先的表
db.execSQL("DROP TABLE LOADED_SONG");
／／重命名表
db.execSQL("ALTER TABLE post2 RENAME TO LOADED_SONG");
／／也可以在新表中添加字段
db.execSQL("ALTER TABLE LOADED_SONG ADD COLUMN USERNAME TEXT");