protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
{
var sequence1 = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
var sequence2 = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[1], new SelectQuery()));
SetOperation setOperation;
switch (methodCall.Method.Name)
{
case "Concat":
case "UnionAll": setOperation = SetOperation.UnionAll; break;
case "Union": setOperation = SetOperation.Union; break;
case "Except": setOperation = SetOperation.Except; break;
case "ExceptAll": setOperation = SetOperation.ExceptAll; break;
case "Intersect": setOperation = SetOperation.Intersect; break;
case "IntersectAll": setOperation = SetOperation.IntersectAll; break;
default:
throw new ArgumentException($"Invalid method name {methodCall.Method.Name}.");
}
var needsEmulation = !builder.DataContext.SqlProviderFlags.IsAllSetOperationsSupported &&
setOperation.In(SetOperation.ExceptAll, SetOperation.IntersectAll)
||
!builder.DataContext.SqlProviderFlags.IsDistinctSetOperationsSupported &&
setOperation.In(SetOperation.Except, SetOperation.Intersect);
if (needsEmulation)
{
// emulation
var sequence = new SubQueryContext(sequence1);
var query = sequence2;
var except = query.SelectQuery;
var sql = sequence.SelectQuery;
if (setOperation.In(SetOperation.Except, SetOperation.Intersect))
{
sql.Select.IsDistinct = true;
}
except.ParentSelect = sql;
if (setOperation.In(SetOperation.Except, SetOperation.ExceptAll))
{
sql.Where.Not.Exists(except);
}
else
{
sql.Where.Exists(except);
}
var keys1 = sequence.ConvertToSql(null, 0, ConvertFlags.All);
var keys2 = query.ConvertToSql(null, 0, ConvertFlags.All);
if (keys1.Length != keys2.Length)
{
throw new InvalidOperationException();
}
for (var i = 0; i < keys1.Length; i++)
{
except.Where
.Expr(keys1[i].Sql)
.Equal
.Expr(keys2[i].Sql);
}
return(sequence);
}
var set1 = new SubQueryContext(sequence1);
var set2 = new SubQueryContext(sequence2);
var setOperator = new SqlSetOperator(set2.SelectQuery, setOperation);
set1.SelectQuery.SetOperators.Add(setOperator);
return(new SetOperationContext(set1, set2, methodCall));
}
public SetOperationContext(SubQueryContext sequence1, SubQueryContext sequence2, MethodCallExpression methodCall, SqlSetOperator setOperator)
: base(sequence1)
{
_isObject =
sequence1.IsExpression(null, 0, RequestFor.Object).Result ||
sequence2.IsExpression(null, 0, RequestFor.Object).Result;
if (_isObject)
{
_type = methodCall.Method.GetGenericArguments()[0];
_unionParameter = Expression.Parameter(_type, "t");
}
// initial sequences
AddSequence(sequence1, null);
AddSequence(sequence2, setOperator);
}
