构建动态SQL查询在C#/。NET3.5的最佳方法是什么?方法、动态、SQL

2023-09-07 10:04:37 作者:空白的缘分。

一个项目我工作的那一刻涉及重构一个C#的COM对象它作为一个数据库访问层的一些SQL 2005数据库。

A project I'm working on at the moment involves refactoring a C# Com Object which serves as a database access layer to some Sql 2005 databases.

的存在code笔者已建成的所有手动使用一个字符串,并且许多if语句来构造相当复杂的SQL语句(〜10联接,> 10分选择的SQL查询,〜15-25那里的条件和GROUPBY的)。基表始终是相同的,但是结构联接,条件和分组依赖于一组参数传递到我的类/方法。

The author of the existent code has built all the sql queries manually using a string and many if-statements to construct the fairly complex sql statement (~10 joins, >10 sub selects, ~15-25 where conditions and GroupBy's). The base table is always the same one, but the structure of joins, conditions and groupings depend on a set of parameters that are passed into my class/method.

构建这样的SQL查询正常工作,但它显然不是一个很优雅的解决方案(和相当难以阅读/理解和维护以及)...我可以只写一个简单的QueryBuilder的自己,但我pretty的肯定,我不是第一个有这样那样的问题,所以我的问题:

Constructing the sql query like this does work but it obviously isn't a very elegant solution (and rather hard to read/understand and maintain as well)... I could just write a simple "querybuilder" myself but I am pretty sure that I am not the first one with this kind of problem, hence my questions:

如何的您的构造数据库查询? 请问C#提供了一种简单的方法来动态构建查询? How do you construct your database queries? Does C# offer an easy way to dynamically build queries?

推荐答案

我用C#和LINQ做类似获得日志过滤用户输入词条的东西(见http://stackoverflow.com/questions/11194/conditional-linq-queries):

I used C# and Linq to do something similar to get log entries filtered on user input (see http://stackoverflow.com/questions/11194/conditional-linq-queries):

IQueryable<Log> matches = m_Locator.Logs;

// Users filter
if (usersFilter)
    matches = matches.Where(l => l.UserName == comboBoxUsers.Text);

 // Severity filter
 if (severityFilter)
     matches = matches.Where(l => l.Severity == comboBoxSeverity.Text);

 Logs = (from log in matches
         orderby log.EventTime descending
         select log).ToList();

编辑:没有在最后一条语句执行,直到.ToList()查询。

The query isn't performed until .ToList() in the last statement.