public override SqlFragment Visit(DbGroupByExpression expression)
{
// first process the input
DbGroupExpressionBinding e = expression.Input;
SelectStatement innerSelect = VisitInputExpressionEnsureSelect(e.Expression, e.VariableName, e.VariableType);
scope.Add(e.GroupVariableName, innerSelect);
SelectStatement select = WrapIfNotCompatible(innerSelect, expression.ExpressionKind);
CollectionType ct = (CollectionType)expression.ResultType.EdmType;
RowType rt = (RowType)ct.TypeUsage.EdmType;
int propIndex = 0;
foreach (DbExpression key in expression.Keys)
{
var fragment = key.Accept(this);
select.AddGroupBy(fragment);
propIndex++;
var colFragment = fragment as ColumnFragment;
if (colFragment != null)
{
colFragment = colFragment.Clone();
colFragment.ColumnAlias = String.Format("K{0}", propIndex);
select.Columns.Add(colFragment);
}
}
for (int agg = 0; agg < expression.Aggregates.Count; agg++)
{
DbAggregate a = expression.Aggregates[agg];
DbFunctionAggregate fa = a as DbFunctionAggregate;
if (fa == null)
{
throw new NotSupportedException();
}
string alias = rt.Properties[propIndex++].Name;
ColumnFragment functionCol = new ColumnFragment(null, null);
functionCol.Literal = HandleFunction(fa, a.Arguments[0].Accept(this));
functionCol.ColumnAlias = alias;
select.Columns.Add(functionCol);
}
return(select);
}
protected internal SelectStatement FuseSelectWithInnerSelect(SelectStatement outer, SelectStatement inner)
{
string oldTableName = (inner.From as TableFragment).Name;
string newTableName = inner.Name;
Dictionary <string, ColumnFragment> dicColumns = new Dictionary <string, ColumnFragment>();
foreach (ColumnFragment cf in inner.Columns)
{
if (cf.ColumnAlias != null)
{
dicColumns.Add(cf.ColumnAlias, cf);
}
}
outer.From = inner.From;
(outer.From as TableFragment).Name = newTableName;
// Dispatch Where
if (outer.Where == null)
{
outer.Where = inner.Where;
}
else if (inner.Where != null)
{
outer.Where = new BinaryFragment()
{
Left = outer.Where, Right = inner.Where, Operator = "AND"
};
}
VisitAndReplaceTableName(outer.Where, oldTableName, newTableName, dicColumns);
// For the next constructions, either is defined on outer or at inner, not both
// Dispatch Limit
if (outer.Limit == null)
{
outer.Limit = inner.Limit;
VisitAndReplaceTableName(outer.Limit, oldTableName, newTableName, dicColumns);
}
// Dispatch GroupBy
if (outer.GroupBy == null && inner.GroupBy != null)
{
foreach (SqlFragment sf in inner.GroupBy)
{
outer.AddGroupBy(sf);
}
foreach (SqlFragment sf in outer.GroupBy)
{
VisitAndReplaceTableName(sf, oldTableName, newTableName, dicColumns);
}
}
// Dispatch OrderBy
if (outer.OrderBy != null || inner.OrderBy != null)
{
if (inner.OrderBy != null)
{
foreach (SortFragment sf in inner.OrderBy)
{
outer.AddOrderBy(sf);
}
}
foreach (SortFragment sf in outer.OrderBy)
{
VisitAndReplaceTableName(sf, oldTableName, newTableName, dicColumns);
}
}
// Dispatch Skip
if (outer.Skip == null)
{
outer.Skip = inner.Skip;
}
return(outer);
}
/// <summary>
/// If input sqlFragment is a group by structure, is flattened to remove some nested correlation queries.
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
private SqlFragment TryFlatteningGroupBy(SqlFragment input)
{
SelectStatement select = null;
SelectStatement tmpFrag = null, tmpFrag2 = null, tmpFrag3 = null;
InputFragment table = null;
string objName = null, colName = null, queryName = null;
// First part assert is a kind-of structure we are looking for
tmpFrag = input as SelectStatement;
if (tmpFrag == null)
{
goto NoChanges;
}
tmpFrag = (tmpFrag).From as SelectStatement;
if (tmpFrag == null)
{
goto NoChanges;
}
queryName = tmpFrag.Name;
if (tmpFrag.Columns.Count < 2)
{
goto NoChanges;
}
if (!(tmpFrag.Columns[0] is ColumnFragment))
{
goto NoChanges;
}
colName = objName = (tmpFrag.Columns[0] as ColumnFragment).ActualColumnName;
tmpFrag2 = tmpFrag.From as SelectStatement;
if (tmpFrag2 == null)
{
goto NoChanges;
}
if (tmpFrag2.Columns.Count < 1 || !(tmpFrag2.Columns[0] is ColumnFragment))
{
goto NoChanges;
}
if (string.CompareOrdinal(objName, tmpFrag2.Columns[0].ActualColumnName) != 0)
{
goto NoChanges;
}
if (tmpFrag.Columns[1].Literal == null)
{
goto NoChanges;
}
tmpFrag2 = tmpFrag.Columns[1].Literal as SelectStatement;
if (tmpFrag2 == null)
{
goto NoChanges;
}
if ((tmpFrag2.Columns.Count != 1) || !(tmpFrag2.Columns[0].Literal != null))
{
goto NoChanges;
}
tmpFrag3 = tmpFrag2.From as SelectStatement;
if (tmpFrag3 == null)
{
goto NoChanges;
}
table = tmpFrag3.From as InputFragment;
if (table == null)
{
goto NoChanges;
}
FunctionFragment func = tmpFrag2.Columns[0].Literal as FunctionFragment;
if (tmpFrag3.Columns.Count != 1 || !(tmpFrag3.Columns[0] is ColumnFragment))
{
goto NoChanges;
}
if (func == null)
{
goto NoChanges;
}
// Yes it is the kind-of type we like, then optimize it
select = new SelectStatement(this);
table.Name = null;
string tableName = null;
TableFragment t = tmpFrag3.From as TableFragment;
if (t == null)
{
tableName = tmpFrag3.Columns[0].TableName;
}
else
{
tableName = t.Table;
}
select.From = table;
select.Columns.Add(new ColumnFragment(tableName, colName));
select.Columns.Add(new ColumnFragment(tableName, "C0")
{
ColumnAlias = "C1",
Literal = new FunctionFragment()
{
Argument = new ColumnFragment(tableName, tmpFrag3.Columns[0].ActualColumnName),
Distinct = tmpFrag3.IsDistinct,
Name = func.Name
}
});
select.Wrap(null);
select.Name = queryName;
select.AddGroupBy(select.Columns[0]);
(input as SelectStatement).From = select;
NoChanges:
return(input);
}
