SQL 联合到 NHibernate 标准

Question

有没有办法将此 SQL 语句转换为 NHibernate Criteria？

(select b1.FieldA as Name, b1.FieldA as FullName from Sale b1 where b1.FieldA like '%john%' or b1.FieldA like '%john%' order by b1.Id desc)
union 
(select b2.FieldC as Name, b2.FieldD as FullName from Sale b2 where b2.FieldC like '%john%' or b2.FieldD like '%john%' order by b2.Id desc)
union 
(select c.FieldE as Name, c.FieldF as FullName from Client c where c.FieldE like '%john%' or c.FieldF like '%john%' order by c.Id desc)

我发现 NHibernate 不支持联合。

Answer 1

尝试使用视图。它可以直接在 NHibernate 中映射，不依赖于特定的数据库实现。您应该删除 where 子句，然后您可以针对“Name”和“FullName”构建您的 NHibernate 标准。

  (select b1.FieldA as Name, b1.FieldA as FullName from Sale b1 order by b1.Id desc)
  union 
  (select b2.FieldC as Name, b2.FieldD as FullName from Sale b2 order by b2.Id desc)
  union 
  (select c.FieldE as Name, c.FieldF as FullName from Client c order by c.Id desc)

Answer 2

所以，我找到了两种解决方案。我分别执行每个查询而不是连接结果。它就像一个联合，但不是在数据库中执行，而是在内存中执行。

var b1 = Session.Query<Sale>()
            .Where(x => x.FiledA.Contains(filter) || x.FiledB.Contains(filter))
            .OrderBy(x => x.Id)
            .GroupBy(x => new { x.FiledA, x.FiledB })
            .Select(x => new Foo { FullName = x.Key.FiledA, Name = x.Key.FiledB })
            .Take(30)
            .ToList();

var b2 = Session.Query<Sale>()
            .Where(x => x.FiledC.Contains(filter) || x.FiledD.Contains(filter))
            .OrderBy(x => x.Id)
            .GroupBy(x => new {x.FiledC, x.FiledD})
            .Select(x => new Foo {FullName = x.Key.FiledC, Name = x.Key.FiledD})
            .Take(30)
            .ToList();


var c = Session.Query<Client>()
            .Where(x => x.FiledE.Contains(filter) || x.FiledF.Contains(filter))
            .OrderBy(x => x.Id)
            .GroupBy(x => new { x.FiledE, x.FiledF })
            .Select(x => new Foo { FullName = x.Key.FiledE, Name = x.Key.FiledF })
            .Take(30)
            .ToList();

return b1.Concat(b2)
         .Concat(c)
         .ToList()
         .GroupBy(x => new { x.Name, x.FullName })
         .Select(x => x.First())
         .Take(30);

或

var b1 = Session.CreateCriteria<Sale>()
    .SetProjection(Projections.ProjectionList()
        .Add(Projections.Distinct(Projections.Property("FiledA")), "Name")
        .Add(Projections.Property("FiledB"), "FullName"))
    .Add(Restrictions.Or(Restrictions.InsensitiveLike("FiledA", filter),
        Restrictions.InsensitiveLike("FiledB", filter)))
    .AddOrder(Order.Desc("Id"))
    .SetMaxResults(30)
    .SetResultTransformer(Transformers.AliasToBean<Foo>())
    .List<Foo>();

var b2 = Session.CreateCriteria<Sale>()
    .SetProjection(Projections.ProjectionList()
        .Add(Projections.Distinct(Projections.Property("FiledC")), "Name")
        .Add(Projections.Property("FiledD"), "FullName"))
    .Add(Restrictions.Or(Restrictions.InsensitiveLike("FiledC", filter),
        Restrictions.InsensitiveLike("FiledD", filter)))
    .AddOrder(Order.Desc("Id"))
    .SetMaxResults(30)
    .SetResultTransformer(Transformers.AliasToBean<Foo>())
    .List<Foo>();

var c = Session.CreateCriteria<Client>()
    .SetProjection(Projections.ProjectionList()
        .Add(Projections.Distinct(Projections.Property("FiledE")), "Name")
        .Add(Projections.Property("FieldF"), "FullName"))
    .Add(Restrictions.Or(Restrictions.InsensitiveLike("FiledE", filter),
        Restrictions.InsensitiveLike("FieldF", filter)))
    .AddOrder(Order.Desc("Id"))
    .SetMaxResults(30)
    .SetResultTransformer(Transformers.AliasToBean<Foo>())
    .List<Foo>();

return b1.Concat(b2)
         .Concat(c)
         .ToList()
         .GroupBy(x => new {x.FullName, x.Name})
         .Select(x => x.First())
         .Take(30);