[4.1.数据库的准备工作](4.1.%E6%95%B0%E6%8D%AE%E5%BA%93%E7%9A%84%E5%87%86%E5%A4%87%E5%B7%A5%E4%BD%9C.md) [4.2.数据库操作简介](4.2.%E6%95%B0%E6%8D%AE%E5%BA%93%E6%93%8D%E4%BD%9C%E7%AE%80%E4%BB%8B.md) [4.3.数据库原生查询实战](4.3.%E6%95%B0%E6%8D%AE%E5%BA%93%E5%8E%9F%E7%94%9F%E6%9F%A5%E8%AF%A2%E5%AE%9E%E6%88%98.md) [4.4.常用查询构造器_1](4.4.%E5%B8%B8%E7%94%A8%E6%9F%A5%E8%AF%A2%E6%9E%84%E9%80%A0%E5%99%A8_1.md) [4.5.常用查询构造器_2](4.5.%E5%B8%B8%E7%94%A8%E6%9F%A5%E8%AF%A2%E6%9E%84%E9%80%A0%E5%99%A8_2.md) [4.6.常用查询构造器_3](4.6.%E5%B8%B8%E7%94%A8%E6%9F%A5%E8%AF%A2%E6%9E%84%E9%80%A0%E5%99%A8_3.md)