public Blob getUrlBlobFromDb(String tableName, String md5FieldName,
			String md5FieldValue) {
		String sql = "select * from " + tableName + " where " + md5FieldName
				+ "='" + md5FieldValue + "'";
		ResultSet rs = executeSelectQuery(sql);
		Blob blob = null;
		try {
			if (rs.next()) {
				if (rs.getBlob("content") != null) {
					blob = rs.getBlob("content");
					// System.out.println(blob.toString());
				} else if (rs.next()) {
					ClsFile.writeLog(dbLogName, "ڶurlϢ" + tableName + "."
							+ md5FieldName + "=" + md5FieldValue);
				}
			} else {
				ClsFile.writeLog(dbLogName, "ݿвڴurlϢ" + tableName + "."
						+ md5FieldName + "=" + md5FieldValue);
			}
			return blob;
		} catch (SQLException e) {
			e.printStackTrace();
			return blob;
		}
	}