哪种方法更好地从数据库检索数据
我对选择两种方法感到困惑。
场景
有两个表，分别是Table 1和Table 2。 表 1 包含用户的数据，例如名字、姓氏等。
表 2 包含每个用户拥有的汽车及其描述。即颜色，注册号等
现在，如果我想获得所有用户的所有信息，那么什么方法最好在最短的时间内完成？
方法 1.
查询表 1 中的所有行并将它们全部存储在列表中。
然后循环遍历列表并根据第一步中保存的用户从表2中获取数据。
方法 2
查询所有行，并在保存该行时从表 2 获取其所有值并保存它们。
如果我想到系统进程，那么我认为它可能是相同的，因为两种方法中要处理的记录数量相同。
如果有其他更好的想法请告诉我
I am confused about selecting two approaches.
Scenario
there are two tables Table 1 and Table 2 respectively. Table 1 contains user's data for example first name, last name etc
Table 2 contains cars each user has with its description. i.e Color, Registration No etc
Now if I want to have all the information of all users then what approach is best to be completed in minimum time?
Approach 1.
Query for all rows in Table 1 and store them all in a list for ex.
then Loop through the list and query it and get data from Table 2 according to user saved in in first step.
Approach 2
Query for all rows and while saving that row get its all values from table 2 and save them too.
If I think of system processes then I think it might be the same because there are same no of records to be processed in both approaches.
If there is any other better idea please let me know
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您的两种方法将具有大致相同的性能（由于 N+1 查询而缓慢）。像这样执行单个查询会更快：
您的客户端应用程序可以解释结果并将所有数据包含在单个查询中。另一种选择是：
这只是伪代码，但您可以使其工作。
union-all 查询将具有令人惊讶的良好性能，因为 sql server 将执行“合并并”，其工作方式类似于合并连接。这种模式也适用于多层次的父子关系，尽管效果不太好。
Your two approaches will have about the same performance (slow because of N+1 queries). It would be faster to do a single query like this:
Your client app can them interpret the results and have all data in a single query. An alternative would be:
This is just pseudo code but you could make it work.
The union-all query will have surprisingly good performance because sql server will do a "merge union" which works like a merge-join. This pattern also works for multi-level parent-child relationships, although not as well.