internal override DbExpression AsCqt(DbExpression row, bool skipIsNotNull)
{
DbExpression cqt = (DbExpression)null;
this.AsCql((Action <NegatedConstant, IEnumerable <Constant> >)((negated, domainValues) => cqt = negated.AsCqt(row, domainValues, this.RestrictedMemberSlot.MemberPath, skipIsNotNull)), (Action <Set <Constant> >)(domainValues =>
{
cqt = this.RestrictedMemberSlot.MemberPath.AsCqt(row);
if (domainValues.Count == 1)
{
cqt = (DbExpression)cqt.Equal(domainValues.Single <Constant>().AsCqt(row, this.RestrictedMemberSlot.MemberPath));
}
else
{
cqt = Helpers.BuildBalancedTreeInPlace <DbExpression>((IList <DbExpression>)domainValues.Select <Constant, DbExpression>((Func <Constant, DbExpression>)(c => (DbExpression)cqt.Equal(c.AsCqt(row, this.RestrictedMemberSlot.MemberPath)))).ToList <DbExpression>(), (Func <DbExpression, DbExpression, DbExpression>)((prev, next) => (DbExpression)prev.Or(next)));
}
}), (Action)(() =>
{
DbExpression right = (DbExpression)this.RestrictedMemberSlot.MemberPath.AsCqt(row).IsNull().Not();
cqt = cqt != null ? (DbExpression)cqt.And(right) : right;
}), (Action)(() =>
{
DbExpression left = (DbExpression)this.RestrictedMemberSlot.MemberPath.AsCqt(row).IsNull();
cqt = cqt != null ? (DbExpression)left.Or(cqt) : left;
}), skipIsNotNull);
return(cqt);
}
public override DbExpression Visit(DbEqualExpression exp)
{
DbExpression left = exp.Left;
DbExpression right = exp.Right;
left = DbExpressionExtension.StripInvalidConvert(left);
right = DbExpressionExtension.StripInvalidConvert(right);
MethodInfo method_Sql_Equals = PublicConstants.MethodInfo_Sql_Equals.MakeGenericMethod(left.Type);
/* Sql.Equals(left, right) */
DbMethodCallExpression left_equals_right = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
left, right
});
if (right.NodeType == DbExpressionType.Parameter || right.NodeType == DbExpressionType.Constant || left.NodeType == DbExpressionType.Parameter || left.NodeType == DbExpressionType.Constant || right.NodeType == DbExpressionType.SubQuery || left.NodeType == DbExpressionType.SubQuery || !left.Type.CanNull() || !right.Type.CanNull())
{
/*
* a.Name == name --> a.Name == name
* a.Id == (select top 1 T.Id from T) --> a.Id == (select top 1 T.Id from T)
* 对于上述查询，我们不考虑 null
*/
left_equals_right.Accept(this);
return(exp);
}
/*
* a.Name == a.XName --> a.Name == a.XName or (a.Name is null and a.XName is null)
*/
/* Sql.Equals(left, null) */
var left_is_null = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
left, DbExpression.Constant(null, left.Type)
});
/* Sql.Equals(right, null) */
var right_is_null = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
right, DbExpression.Constant(null, right.Type)
});
/* Sql.Equals(left, null) && Sql.Equals(right, null) */
var left_is_null_and_right_is_null = DbExpression.And(left_is_null, right_is_null);
/* Sql.Equals(left, right) || (Sql.Equals(left, null) && Sql.Equals(right, null)) */
var left_equals_right_or_left_is_null_and_right_is_null = DbExpression.Or(left_equals_right, left_is_null_and_right_is_null);
left_equals_right_or_left_is_null_and_right_is_null.Accept(this);
return(exp);
}
internal override DbExpression AsCqt(DbExpression row, bool skipIsNotNull)
{
DbExpression cqt = null;
AsCql(
// negatedConstantAsCql action
(negated, domainValues) =>
{
Debug.Assert(cqt == null, "unexpected construction order - cqt must be null");
cqt = negated.AsCqt(row, domainValues, RestrictedMemberSlot.MemberPath, skipIsNotNull);
},
// varInDomain action
(domainValues) =>
{
Debug.Assert(cqt == null, "unexpected construction order - cqt must be null");
Debug.Assert(domainValues.Count > 0, "domain must not be empty");
cqt = RestrictedMemberSlot.MemberPath.AsCqt(row);
if (domainValues.Count == 1)
{
// Single value
cqt = cqt.Equal(domainValues.Single().AsCqt(row, RestrictedMemberSlot.MemberPath));
}
else
{
// Multiple values: build list of var = c1, var = c2, ..., then OR them all.
var operands =
domainValues.Select(c => (DbExpression)cqt.Equal(c.AsCqt(row, RestrictedMemberSlot.MemberPath))).ToList();
cqt = Helpers.BuildBalancedTreeInPlace(operands, (prev, next) => prev.Or(next));
}
},
// varIsNotNull action
() =>
{
// ( ... AND var IS NOT NULL)
DbExpression varIsNotNull = RestrictedMemberSlot.MemberPath.AsCqt(row).IsNull().Not();
cqt = cqt != null ? cqt.And(varIsNotNull) : varIsNotNull;
},
// varIsNull action
() =>
{
// (var IS NULL OR ...)
DbExpression varIsNull = RestrictedMemberSlot.MemberPath.AsCqt(row).IsNull();
cqt = cqt != null ? varIsNull.Or(cqt) : varIsNull;
},
skipIsNotNull);
return(cqt);
}
public void Process(DbMethodCallExpression exp, SqlGenerator generator)
{
DbExpression e = exp.Arguments.First();
DbEqualExpression equalNullExpression = DbExpression.Equal(e, DbExpression.Constant(null, UtilConstants.TypeOfString));
DbEqualExpression equalEmptyExpression = DbExpression.Equal(e, DbExpression.Constant(string.Empty));
DbOrExpression orExpression = DbExpression.Or(equalNullExpression, equalEmptyExpression);
DbCaseWhenExpression.WhenThenExpressionPair whenThenPair = new DbCaseWhenExpression.WhenThenExpressionPair(orExpression, DbConstantExpression.One);
List<DbCaseWhenExpression.WhenThenExpressionPair> whenThenExps = new List<DbCaseWhenExpression.WhenThenExpressionPair>(1);
whenThenExps.Add(whenThenPair);
DbCaseWhenExpression caseWhenExpression = DbExpression.CaseWhen(whenThenExps, DbConstantExpression.Zero, UtilConstants.TypeOfBoolean);
var eqExp = DbExpression.Equal(caseWhenExpression, DbConstantExpression.One);
eqExp.Accept(generator);
}
public override DbExpression Visit(DbNotEqualExpression exp)
{
DbExpression left = exp.Left;
DbExpression right = exp.Right;
left = DbExpressionExtension.StripInvalidConvert(left);
right = DbExpressionExtension.StripInvalidConvert(right);
MethodInfo method_Sql_NotEquals = PublicConstants.MethodInfo_Sql_NotEquals.MakeGenericMethod(left.Type);
/* Sql.NotEquals(left, right) */
DbMethodCallExpression left_not_equals_right = DbExpression.MethodCall(null, method_Sql_NotEquals, new List <DbExpression>(2)
{
left, right
});
//明确 left right 其中一边一定为 null
if (DbExpressionExtension.AffirmExpressionRetValueIsNull(right) || DbExpressionExtension.AffirmExpressionRetValueIsNull(left))
{
/*
* a.Name != null --> a.Name != null
*/
left_not_equals_right.Accept(this);
return(exp);
}
if (right.NodeType == DbExpressionType.SubQuery || left.NodeType == DbExpressionType.SubQuery)
{
/*
* a.Id != (select top 1 T.Id from T) --> a.Id <> (select top 1 T.Id from T)，对于这种查询，我们不考虑 null
*/
left_not_equals_right.Accept(this);
return(exp);
}
MethodInfo method_Sql_Equals = PublicConstants.MethodInfo_Sql_Equals.MakeGenericMethod(left.Type);
if (left.NodeType == DbExpressionType.Parameter || left.NodeType == DbExpressionType.Constant)
{
var t = right;
right = left;
left = t;
}
if (right.NodeType == DbExpressionType.Parameter || right.NodeType == DbExpressionType.Constant)
{
/*
* 走到这说明 name 不可能为 null
* a.Name != name --> a.Name <> name or a.Name is null
*/
if (left.NodeType != DbExpressionType.Parameter && left.NodeType != DbExpressionType.Constant)
{
/*
* a.Name != name --> a.Name <> name or a.Name is null
*/
/* Sql.Equals(left, null) */
var left_is_null1 = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
left, DbExpression.Constant(null, left.Type)
});
/* Sql.NotEquals(left, right) || Sql.Equals(left, null) */
var left_not_equals_right_or_left_is_null = DbExpression.Or(left_not_equals_right, left_is_null1);
left_not_equals_right_or_left_is_null.Accept(this);
}
else
{
/*
* name != name1 --> name <> name，其中 name 和 name1 都为变量且都不可能为 null
*/
left_not_equals_right.Accept(this);
}
return(exp);
}
/*
* a.Name != a.XName --> a.Name <> a.XName or (a.Name is null and a.XName is not null) or (a.Name is not null and a.XName is null)
* ## a.Name != a.XName 不能翻译成：not (a.Name == a.XName or (a.Name is null and a.XName is null))，因为数据库里的 not 有时候并非真正意义上的“取反”！
* 当 a.Name 或者 a.XName 其中一个字段有为 NULL，另一个字段有值时，会查不出此条数据 ##
*/
DbConstantExpression null_Constant = DbExpression.Constant(null, left.Type);
/* Sql.Equals(left, null) */
var left_is_null = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
left, null_Constant
});
/* Sql.NotEquals(left, null) */
var left_is_not_null = DbExpression.MethodCall(null, method_Sql_NotEquals, new List <DbExpression>(2)
{
left, null_Constant
});
/* Sql.Equals(right, null) */
var right_is_null = DbExpression.MethodCall(null, method_Sql_Equals, new List <DbExpression>(2)
{
right, null_Constant
});
/* Sql.NotEquals(right, null) */
var right_is_not_null = DbExpression.MethodCall(null, method_Sql_NotEquals, new List <DbExpression>(2)
{
right, null_Constant
});
/* Sql.Equals(left, null) && Sql.NotEquals(right, null) */
var left_is_null_and_right_is_not_null = DbExpression.And(left_is_null, right_is_not_null);
/* Sql.NotEquals(left, null) && Sql.Equals(right, null) */
var left_is_not_null_and_right_is_null = DbExpression.And(left_is_not_null, right_is_null);
/* (Sql.Equals(left, null) && Sql.NotEquals(right, null)) || (Sql.NotEquals(left, null) && Sql.Equals(right, null)) */
var left_is_null_and_right_is_not_null_or_left_is_not_null_and_right_is_null = DbExpression.Or(left_is_null_and_right_is_not_null, left_is_not_null_and_right_is_null);
/* Sql.NotEquals(left, right) || (Sql.Equals(left, null) && Sql.NotEquals(right, null)) || (Sql.NotEquals(left, null) && Sql.Equals(right, null)) */
var e = DbExpression.Or(left_not_equals_right, left_is_null_and_right_is_not_null_or_left_is_not_null_and_right_is_null);
e.Accept(this);
return(exp);
}
// <summary>
// This method is used for translating <see cref="DbIntersectExpression" /> and <see cref="DbExceptExpression" />,
// and for translating the "Except" part of <see cref="DbSkipExpression" />.
// into the follwoing expression:
// A INTERSECT B, A EXCEPT B
// (DISTINCT)
// |
// FILTER
// |
// | - Input: A
// | - Predicate:(NOT)
// |
// ANY
// |
// | - Input: B
// | - Predicate: (B.b1 = A.a1 or (B.b1 is null and A.a1 is null))
// AND (B.b2 = A.a2 or (B.b2 is null and A.a2 is null))
// AND ...
// AND (B.bn = A.an or (B.bn is null and A.an is null)))
// Here, A corresponds to right and B to left.
// (NOT) is present when transforming Except
// for the purpose of translating <see cref="DbExceptExpression" /> or <see cref="DbSkipExpression" />.
// (DISTINCT) is present when transforming for the purpose of translating
// <see cref="DbExceptExpression" /> or <see cref="DbIntersectExpression" />.
// For <see cref="DbSkipExpression" />, the input to ANY is caped with project which projects out only
// the columns represented in the sortExpressionsOverLeft list and only these are used in the predicate.
// This is because we want to support skip over input with non-equal comarable columns and we have no way to recognize these.
// </summary>
// <param name="sortExpressionsOverLeft"> note that this list gets destroyed by this method </param>
private DbExpression TransformIntersectOrExcept(
DbExpression left, DbExpression right, DbExpressionKind expressionKind, IList <DbPropertyExpression> sortExpressionsOverLeft,
string sortExpressionsBindingVariableName)
{
var negate = (expressionKind == DbExpressionKind.Except) || (expressionKind == DbExpressionKind.Skip);
var distinct = (expressionKind == DbExpressionKind.Except) || (expressionKind == DbExpressionKind.Intersect);
var leftInputBinding = left.Bind();
var rightInputBinding = right.Bind();
IList <DbPropertyExpression> leftFlattenedProperties = new List <DbPropertyExpression>();
IList <DbPropertyExpression> rightFlattenedProperties = new List <DbPropertyExpression>();
FlattenProperties(leftInputBinding.Variable, leftFlattenedProperties);
FlattenProperties(rightInputBinding.Variable, rightFlattenedProperties);
//For Skip, we need to ignore any columns that are not in the original sort list. We can recognize these by comparing the left flattened properties and
// the properties in the list sortExpressionsOverLeft
// If any such columns exist, we need to add an additional project, to keep the rest of the columns from being projected, as if any among these
// are non equal comparable, SQL Server 2000 throws.
if (expressionKind == DbExpressionKind.Skip)
{
if (RemoveNonSortProperties(
leftFlattenedProperties, rightFlattenedProperties, sortExpressionsOverLeft, leftInputBinding.VariableName,
sortExpressionsBindingVariableName))
{
rightInputBinding = CapWithProject(rightInputBinding, rightFlattenedProperties);
}
}
Debug.Assert(
leftFlattenedProperties.Count == rightFlattenedProperties.Count,
"The left and the right input to INTERSECT or EXCEPT have a different number of properties");
Debug.Assert(leftFlattenedProperties.Count != 0, "The inputs to INTERSECT or EXCEPT have no properties");
//Build the predicate for the quantifier:
// (B.b1 = A.a1 or (B.b1 is null and A.a1 is null))
// AND (B.b2 = A.a2 or (B.b2 is null and A.a2 is null))
// AND ...
// AND (B.bn = A.an or (B.bn is null and A.an is null)))
DbExpression existsPredicate = null;
for (var i = 0; i < leftFlattenedProperties.Count; i++)
{
//A.ai == B.bi
DbExpression equalsExpression = leftFlattenedProperties[i].Equal(rightFlattenedProperties[i]);
//A.ai is null AND B.bi is null
DbExpression leftIsNullExpression = leftFlattenedProperties[i].IsNull();
DbExpression rightIsNullExpression = rightFlattenedProperties[i].IsNull();
DbExpression bothNullExpression = leftIsNullExpression.And(rightIsNullExpression);
DbExpression orExpression = equalsExpression.Or(bothNullExpression);
if (i == 0)
{
existsPredicate = orExpression;
}
else
{
existsPredicate = existsPredicate.And(orExpression);
}
}
//Build the quantifier
DbExpression quantifierExpression = rightInputBinding.Any(existsPredicate);
DbExpression filterPredicate;
//Negate if needed
if (negate)
{
filterPredicate = quantifierExpression.Not();
}
else
{
filterPredicate = quantifierExpression;
}
//Build the filter
DbExpression result = leftInputBinding.Filter(filterPredicate);
//Apply distinct in needed
if (distinct)
{
result = result.Distinct();
}
return(result);
}
protected override Expression VisitBinary(BinaryExpression node)
{
var expression = base.VisitBinary(node) as BinaryExpression;
DbExpression dbExpression;
// Need special handling for comparisons against the null constant. If we don't translate these
// using an "IsNull" expression, EF will convert it literally as "= null" which doesn't work in SQL Server.
if (IsNullConstantExpression(expression.Right))
{
dbExpression = MapNullComparison(expression.Left, expression.NodeType);
}
else if (IsNullConstantExpression(expression.Left))
{
dbExpression = MapNullComparison(expression.Right, expression.NodeType);
}
else
{
DbExpression leftExpression = GetDbExpressionForExpression(expression.Left);
DbExpression rightExpression = GetDbExpressionForExpression(expression.Right);
switch (expression.NodeType)
{
case ExpressionType.Equal:
// DbPropertyExpression = class property that has been mapped to a database column
// DbParameterReferenceExpression = lambda parameter
if (IsNullableExpressionOfType <DbPropertyExpression>(leftExpression) && IsNullableExpressionOfType <DbParameterReferenceExpression>(rightExpression))
{
dbExpression = CreateEqualComparisonOfNullablePropToNullableParam(leftExpression, rightExpression);
}
else if (IsNullableExpressionOfType <DbPropertyExpression>(rightExpression) && IsNullableExpressionOfType <DbParameterReferenceExpression>(leftExpression))
{
dbExpression = CreateEqualComparisonOfNullablePropToNullableParam(rightExpression, leftExpression);
}
else
{
dbExpression = leftExpression.Equal(rightExpression);
}
break;
case ExpressionType.NotEqual:
dbExpression = leftExpression.NotEqual(rightExpression);
break;
case ExpressionType.GreaterThan:
dbExpression = leftExpression.GreaterThan(rightExpression);
break;
case ExpressionType.GreaterThanOrEqual:
dbExpression = leftExpression.GreaterThanOrEqual(rightExpression);
break;
case ExpressionType.LessThan:
dbExpression = leftExpression.LessThan(rightExpression);
break;
case ExpressionType.LessThanOrEqual:
dbExpression = leftExpression.LessThanOrEqual(rightExpression);
break;
case ExpressionType.AndAlso:
dbExpression = leftExpression.And(rightExpression);
break;
case ExpressionType.OrElse:
dbExpression = leftExpression.Or(rightExpression);
break;
default:
throw new NotImplementedException(string.Format("Unhandled NodeType of {0} in LambdaToDbExpressionVisitor.VisitBinary", expression.NodeType));
}
}
MapExpressionToDbExpression(expression, dbExpression);
return(expression);
}
