LINQ 选择中的 C# 子查询

Posted 2023-02-16

【中文标题】LINQ 选择中的 C# 子查询

【英文标题】：C# subquery in LINQ select

【发布时间】：2021-12-07 17:18:23

【问题描述】：

我正在尝试将此查询转换为 LINQ，但我没有得到子查询的值

查询：

select c.cod, c.cpfcnpj, c.razaosocial, c.nome, c.fone, c.celular, c.email, c.dtcad, s.dataval as validade,
(select max(datapagamento) from vendas where c.cod = coduser) as datapag
from usuarios c, libsys s
WHERE c.cod = s.codcli
and c.cod in (select coduser from vendas)
AND c.cod in (select l.codcli from libsys l where l.dataval >= current_date)
order by c.dtcad asc

LINQ：

        var rel = await (from u in _contexto.usuarios
                         from v in _contexto.libsys
                         where (
                                 (u.cod == v.codcli) &&
                                 _contexto.vendas.Any(y => y.coduser == u.cod) &&
                                 _contexto.libsys.Any(y => y.codcli == u.cod && y.pcpdataval >= System.DateTime.Now)
                               )
                         select new RelatorioLicsModel
                         
                             
                             cod = u.cod,
                             cpfcnpj = u.cpfcnpj,
                             razaosocial = u.razaosocial,
                             nome = u.nome,
                             fone = u.fone,
                             celular = u.celular,
                             email = u.email,
                             dtcad = u.dtcad,
                             validade = v.pcpdataval.ToString(),
                             dtpag = Convert.ToDateTime(_contexto.vendas.Where(s => s.datapagamento == _contexto.vendas.Max(x => x.datapagamento) && s.coduser == u.cod).FirstOrDefault())
                         ).ToListAsync();

我得到的错误是：

“您的 SQL 语法有错误；请查看与您的 mysql 服务器版本相对应的手册，了解在 '(PARTITION BY v.coduser ORDER BY v 附近使用的正确语法.cod) AS row\r\n FROM vendas ' 在第 7 行"

这是正确的方法吗？感谢您的帮助！

【参考方案1】：

dtpag 属性存在问题。

var query = 
    from u in _contexto.usuarios
    from v in _contexto.libsys
    where (
            (u.cod == v.codcli) &&
            _contexto.vendas.Any(y => y.coduser == u.cod) &&
            _contexto.libsys.Any(y => y.codcli == u.cod && y.pcpdataval >= System.DateTime.Now)
        )
    select new RelatorioLicsModel
    
        
        cod = u.cod,
        cpfcnpj = u.cpfcnpj,
        razaosocial = u.razaosocial,
        nome = u.nome,
        fone = u.fone,
        celular = u.celular,
        email = u.email,
        dtcad = u.dtcad,
        validade = v.pcpdataval.ToString(),
        dtpag = Convert.ToDateTime(_contexto.vendas.Where(s => s.coduser == u.cod).Max(x => x.datapagamento))