NOT IN sub select 从 T SQL 到 LINQ？

Question

尝试在此处编写 LINQ 查询以从 T SQL 复制 NOT IN。这是我在 LINQ 中想要的 SQL 查询：

select * from schema.Table1
where TableId NOT IN (select pa.TableId from schema.Table2 ta
where ta.SecondaryId = myParameter)

看过以前的帖子，但还没完全弄明白。

var query = from a in _Context.Table1
                    where a.TableId != _Context.Table2.Any(ta=>(ta.SecondaryId== myParameter))
                    select a;

Answer 1

您可以尝试这样的操作：

// get all the values that you want to exclude in a list.
var excluded = (from t in _Context.TableId
                select t.TableId
                where t.SecondaryId == myParameter).ToList();

// get all the items from Table1 that aren't contained in the above list
var query = from t in _Context.Table1
            where excluded.Contains(t.TableId)==false
            select t;

或

// get all the values that you want to exclude in a list.
var excluded = _Context.TableId
                       .Where(x=>x.SecondaryId == myParameter)
                       .Select(x=>x.TableId)
                       .ToList();

// get all the items from Table1 that aren't contained in the above list
var query = _Context.Table1.Where(a=>!excluded.Any(a.TableId));

Answer 2

var query = from a in _Context.Table1
            where _Context.Table2.Any(ta=>ta.SecondaryId== a.TableId) == false
            select a;

Answer 3

您也许可以做到这一点...它并不漂亮...但考虑到 LinqToSQL 的有限功能集，它可能会起作用

IQueryable<Table2> excluded = from t in _Context.Table2
                           where t.SecondaryId == myParameter
                           select t;

// get all the items from Table1 that aren't contained in the above list
IQueryable<Table1> query = from t1 in _Context.Table1
                           join t2 in excluded on t1.TableId equals t2.TableId into foo
                           from e in foo.DefaultIfEmpty()
                           where e == null
                           select t;

此查询的结果应等同于

SELECT t1.*
FROM Table1 t1
LEFT JOIN (SELECT * FROM Table2 WHERE SecondaryId == @myParameter) t2 
          ON t1.TableId = t2.TableId
WHERE t2.TableId IS NULL

NOT IN sub select 从 T SQL 到 LINQ？

NOT IN sub select from T SQL to LINQ?

c#

linq

sql-server