c# - PredicateBuilder 剥离括号，打破嵌套的 AND 与 OR 的组合

Question

如何PredicateBuilder用于将带有嵌套 AND 的多个语句或在一起，而不去除括号？

我们试图得到:

(fieldA = X AND fieldB = Y AND fieldC = Z)  or (fieldA = A AND fieldB = B and fieldC = C)

但是下面的代码生成了(注意没有括号，意思是数据库查询返回了错误的数据)

fieldA = X AND fieldB = Y AND fieldC = Z  or fieldA = A AND fieldB = B and fieldC = C

我们正在像这样构建谓词:

var predicate = PredicateBuilder.False<MonitoredService>();

foreach (var a in affected)
{
    var a1 = a;
    predicate = predicate.Or(m => m.ItemId == a1.ItemId && m.MinSeverity <= a1.Severity && m.LastUpdatedUtc <= a1.LastModifiedUtc);
}

var monitors = _monitoredServiceRepository.List(predicate);

Answer 1

在 LINQ 和 SQL Server 中(我很肯定这也是 MySQL、Oracle 和其他数据库的情况)，先评估 AND 运算符，然后再评估 OR 运算符。

所以

(fieldA = X AND fieldB = Y AND fieldC = Z)  or (fieldA = A AND fieldB = B and fieldC = C)

与

相同

fieldA = X AND fieldB = Y AND fieldC = Z  or fieldA = A AND fieldB = B and fieldC = C