fix links in ch7 & ch8

ddia/ch7.md

@@ -412,7 +412,7 @@ UPDATE counters SET value = value + 1 WHERE key = 'foo';
 
 例如，考虑一个多人游戏，其中几个玩家可以同时移动相同的棋子。在这种情况下，一个原子操作可能是不够的，因为应用程序还需要确保玩家的移动符合游戏规则，这可能涉及到一些不能合理地用数据库查询实现的逻辑。但你可以使用锁来防止两名玩家同时移动相同的棋子，如例7-1所示。
 
-##### 例7-1 显式锁定行以防止丢失更新
+**例7-1 显式锁定行以防止丢失更新**
 
 ```plsql
 BEGIN TRANSACTION;
@@ -895,10 +895,8 @@ WHERE room_id = 123 AND
    “[The Notions of Consistency and Predicate Locks in a Database System](http://research.microsoft.com/en-us/um/people/gray/papers/On%20the%20Notions%20of%20Consistency%20and%20Predicate%20Locks%20in%20a%20Database%20System%20CACM.pdf),” *Communications of the
    ACM*, volume 19, number 11, pages 624–633, November 1976.
 4. “[ACID Transactions Are Incredibly Helpful](http://web.archive.org/web/20150320053809/https://foundationdb.com/acid-claims),” FoundationDB, LLC, 2013.
-5. John D. Cook:
-   “[ACID Versus BASE for Database Transactions](http://www.johndcook.com/blog/2009/07/06/brewer-cap-theorem-base/),” *johndcook.com*, July 6, 2009.
-6. Gavin Clarke:
-   “[NoSQL's CAP Theorem Busters: We Don't Drop ACID](http://www.theregister.co.uk/2012/11/22/foundationdb_fear_of_cap_theorem/),” *theregister.co.uk*, November 22, 2012.
+5. John D. Cook: “[ACID Versus BASE for Database Transactions](http://www.johndcook.com/blog/2009/07/06/brewer-cap-theorem-base/),” *johndcook.com*, July 6, 2009.
+6. Gavin Clarke: “[NoSQL's CAP Theorem Busters: We Don't Drop ACID](http://www.theregister.co.uk/2012/11/22/foundationdb_fear_of_cap_theorem/),” *theregister.co.uk*, November 22, 2012.
 7. Theo Härder and Andreas Reuter:
    “[Principles of Transaction-Oriented Database Recovery](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.87.2812&rep=rep1&type=pdf),” *ACM Computing Surveys*,
    volume 15, number 4, pages 287–317, December 1983.