database/gdb: enhance the underlying data transformation when querying data #3557
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wln32
changed the title
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代码量有点多，需要花点时间review。 |
The amount of code is a bit large and it will take some time. |
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本次改动只修改了Scan方法的底层的类型转换实现，会走新的逻辑，依旧是先把数据转换到map，然后在转到结构体上，
和之前的行为保持一致，不会导致不兼容。
从map到结构体的转换和之前不同的是，由于在底层转换时已经转成了具体类型，不需要调用gconv来做转换，可以直接使用循环赋值
未修改之前的
修改后的
性能方面大幅提升，如果是直接一步赋值到结构体上，只需要600ms，但这样会导致有些api不兼容
一些建议
和orm的转换有关的接口，应当实现Scan和Value这两个接口来做，和标准库保持一致
建议废弃掉All，One之类的方法，一点都不好用，如果查询的是单个字段，或者是一个[]int，还需要再次转换才能使用，不如直接把Scan方法加强，支持 int , []int 这种类型的参数，一步赋值到目标字段，而不是走中间变量来回重复的转换
关于HookFuncSelect 的Next方法的返回值，不应该把原始的数据结构暴漏出去让用户操作，应当封装到结构体内部，通过方法去操作