本文整理汇总了C#中DbExpression.Equal方法的典型用法代码示例。如果您正苦于以下问题：C# DbExpression.Equal方法的具体用法？C# DbExpression.Equal怎么用？C# DbExpression.Equal使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类DbExpression的用法示例。
在下文中一共展示了DbExpression.Equal方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C#代码示例。
示例1: ImplementEqualityUnknownArguments
// Generate an equality expression where the values of the left and right operands are completely unknown
private DbExpression ImplementEqualityUnknownArguments(DbExpression left, DbExpression right, EqualsPattern pattern)
{
switch (pattern)
{
case EqualsPattern.Store: // left EQ right
return left.Equal(right);
case EqualsPattern.PositiveNullEqualityNonComposable: // for Joins
return left.Equal(right).Or(left.IsNull().And(right.IsNull()));
case EqualsPattern.PositiveNullEqualityComposable:
{
var bothNotNull = left.Equal(right);
var bothNull = left.IsNull().And(right.IsNull());
if (!_funcletizer.RootContext.ContextOptions.UseCSharpNullComparisonBehavior)
{
return bothNotNull.Or(bothNull); // same as EqualsPattern.PositiveNullEqualityNonComposable
}
// add more logic to avoid undefined result for true clr semantics, ensuring composability
// (left EQ right AND NOT (left IS NULL OR right IS NULL)) OR (left IS NULL AND right IS NULL)
var anyOneIsNull = left.IsNull().Or(right.IsNull());
return (bothNotNull.And(anyOneIsNull.Not())).Or(bothNull);
}
default:
Debug.Fail("unexpected pattern");
return null;
}
}示例2: ImplementEquality
// For comparisons, where the left and right side are nullable or not nullable,
// here are the (compositionally safe) null equality predicates:
// -- x NOT NULL, y NULL
// x = y AND NOT (y IS NULL)
// -- x NULL, y NULL
// (x = y AND (NOT (x IS NULL OR y IS NULL))) OR (x IS NULL AND y IS NULL)
// -- x NOT NULL, y NOT NULL
// x = y
// -- x NULL, y NOT NULL
// x = y AND NOT (x IS NULL)
private DbExpression ImplementEquality(DbExpression left, DbExpression right, EqualsPattern pattern)
{
switch (left.ExpressionKind)
{
case DbExpressionKind.Constant:
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant: // constant EQ constant
return left.Equal(right);
case DbExpressionKind.Null: // null EQ constant --> false
return DbExpressionBuilder.False;
default:
return ImplementEqualityConstantAndUnknown((DbConstantExpression)left, right, pattern);
}
case DbExpressionKind.Null:
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant: // null EQ constant --> false
return DbExpressionBuilder.False;
case DbExpressionKind.Null: // null EQ null --> true
return DbExpressionBuilder.True;
default: // null EQ right --> right IS NULL
return right.IsNull();
}
default: // unknown
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant:
return ImplementEqualityConstantAndUnknown((DbConstantExpression)right, left, pattern);
case DbExpressionKind.Null: // left EQ null --> left IS NULL
return left.IsNull();
default:
return ImplementEqualityUnknownArguments(left, right, pattern);
}
}
}