安卓数据库查询细节

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// 判断users表中的是否包含某个UserID的记录public UserInfo GetUserByName(String userName) {Boolean b = false;// 注意汉字为查询条件时需要加''Cursor cursor = db.query(SqliteHelper.TB_NAME, null, UserInfo.USERNAME+ "='" + userName + "'", null, null, null, null);b = cursor.moveToFirst();Log.e("GetUserByName", b.toString());if (b != false) {UserInfo user = new UserInfo();user.setId(cursor.getString(0));user.setUserId(cursor.getString(1));user.setToken(cursor.getString(2));user.setTokenSecret(cursor.getString(3));user.setUserName(cursor.getString(4));ByteArrayInputStream stream = new ByteArrayInputStream(cursor.getBlob(5));Drawable icon = Drawable.createFromStream(stream, "image");user.setUserIcon(icon);cursor.close();return user;}return null;}

特别注意如果查询条件为汉字时，需要加 ' ' 如：Cursor cursor = db.query(SqliteHelper.TB_NAME, null, UserInfo.USERNAME + "='" + userName + "'", null, null, null, null);
另外，如果需要在数据库中创建图片信息是三步：

ByteArrayInputStream stream = new ByteArrayInputStream( cursor.getBlob(5) );

Drawable icon = Drawable.createFromStream(stream, "image");

user.setUserIcon(icon);

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