protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
{
var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0])
{
CreateSubQuery = true
});
var prevSequence = sequence;
// Wrap by subquery to handle aggregate limitations, especially for SQL Server
//
sequence = new SubQueryContext(sequence);
if (prevSequence.SelectQuery.OrderBy.Items.Count > 0)
{
if (prevSequence.SelectQuery.Select.TakeValue == null && prevSequence.SelectQuery.Select.SkipValue == null)
{
prevSequence.SelectQuery.OrderBy.Items.Clear();
}
}
var context = new AggregationContext(buildInfo.Parent, sequence, methodCall);
var methodName = methodCall.Method.Name.Replace("Async", "");
var sql = sequence.ConvertToSql(null, 0, ConvertFlags.Field).Select(_ => _.Sql).ToArray();
if (sql.Length == 1)
{
if (sql[0] is SelectQuery query)
{
if (query.Select.Columns.Count == 1)
{
var join = query.OuterApply();
context.SelectQuery.From.Tables[0].Joins.Add(join.JoinedTable);
sql[0] = query.Select.Columns[0];
}
}
}
ISqlExpression sqlExpression = new SqlFunction(methodCall.Type, methodName, true, sql);
if (sqlExpression == null)
{
throw new LinqToDBException("Invalid Aggregate function implementation");
}
context.Sql = context.SelectQuery;
context.FieldIndex = context.SelectQuery.Select.Add(sqlExpression, methodName);
return(context);
}
protected override IBuildContext BuildMethodCall(ExpressionBuilder builder, MethodCallExpression methodCall, BuildInfo buildInfo)
{
var sequence = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[0]));
var query = builder.BuildSequence(new BuildInfo(buildInfo, methodCall.Arguments[1], new SelectQuery()));
var except = query.SelectQuery;
sequence = new SubQueryContext(sequence);
var sql = sequence.SelectQuery;
except.ParentSelect = sql;
if (methodCall.Method.Name == "Except")
{
sql.Where.Not.Exists(except);
}
else
{
sql.Where.Exists(except);
}
var keys1 = sequence.ConvertToSql(null, 0, ConvertFlags.Key);
var keys2 = query.ConvertToSql(null, 0, ConvertFlags.Key);
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);
}
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));
}