public override SqlFragment Visit(DbElementExpression expression)
{
SelectStatement s = VisitInputExpressionEnsureSelect(expression.Argument, null, null);
s.Wrap(scope);
return(s);
}
public SelectStatement WrapIfNotCompatible(SelectStatement select, DbExpressionKind expressionKind)
{
if (select.IsCompatible(expressionKind))
{
return(select);
}
SelectStatement newSelect = new SelectStatement(this);
select.Wrap(scope);
select.Scoped = true;
newSelect.From = select;
return(newSelect);
}
private InputFragment WrapJoinInputIfNecessary(InputFragment fragment, bool isRightPart)
{
if (fragment is SelectStatement || fragment is UnionFragment)
{
fragment.Wrap(scope);
fragment.Scoped = true;
}
else if (fragment is JoinFragment && isRightPart)
{
SelectStatement select = new SelectStatement(this);
select.From = fragment;
select.Name = fragment.Name;
select.Wrap(scope);
return(select);
}
return(fragment);
}
/// <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);
}
public override SqlFragment Visit(DbApplyExpression expression)
{
DbExpressionBinding inputBinding = expression.Input;
InputFragment input = VisitInputExpression(inputBinding.Expression, inputBinding.VariableName, inputBinding.VariableType);
DbExpressionBinding applyBinding = expression.Apply;
InputFragment apply = VisitInputExpression(applyBinding.Expression, applyBinding.VariableName, applyBinding.VariableType);
SelectStatement select = new SelectStatement(this);
bool isInputSelect = false;
if (!(input is TableFragment))
{
input.Wrap(scope);
isInputSelect = true;
}
apply.Wrap(scope);
select.From = input;
select.Wrap(scope);
if (apply is SelectStatement)
{
SelectStatement applySel = apply as SelectStatement;
foreach (ColumnFragment f in applySel.Columns)
{
SelectStatement newColSelect = new SelectStatement(this);
newColSelect.From = applySel.From;
newColSelect.Where = applySel.Where;
if (isInputSelect)
{
VisitAndReplaceTableName(newColSelect.Where, (input as SelectStatement).From.Name, input.Name, null);
}
newColSelect.Limit = applySel.Limit;
newColSelect.OrderBy = applySel.OrderBy;
newColSelect.Skip = applySel.Skip;
newColSelect.GroupBy = applySel.GroupBy;
newColSelect.IsDistinct = applySel.IsDistinct;
newColSelect.Columns.Add(f);
newColSelect.Wrap(scope);
scope.Add(applySel.From.Name, applySel.From);
ColumnFragment newCol = new ColumnFragment(apply.Name, f.ColumnName);
newCol.Literal = newColSelect;
newCol.PushInput(newCol.ColumnName);
newCol.PushInput(apply.Name);
select.AddColumn(newCol, scope);
if (string.IsNullOrEmpty(newCol.ColumnAlias))
{
newColSelect.Name = newCol.ColumnName;
newCol.ColumnAlias = newCol.ColumnName;
}
scope.Remove(newColSelect);
}
scope.Remove(applySel.From);
scope.Remove(apply);
}
else if (apply is UnionFragment)
{
UnionFragment uf = apply as UnionFragment;
if (uf.Left == null || uf.Right == null)
{
throw new Exception("Union fragment is not properly formed.");
}
var left = uf.Left as SelectStatement;
var right = uf.Right as SelectStatement;
if (left == null || right == null)
{
throw new NotImplementedException();
}
var whereleft = left.Where as BinaryFragment;
var whereright = right.Where as BinaryFragment;
if (whereleft == null || whereright == null)
{
throw new NotImplementedException();
}
LiteralFragment literalFragmentWhere = null;
//checking where left
if (whereleft.Left is ColumnFragment && whereleft.Right is ColumnFragment)
{
// we replace the where part for a dummy one
if (whereright.Left is ColumnFragment && whereright.Right is ColumnFragment)
{
literalFragmentWhere = new LiteralFragment("1 = 1");
}
}
if (literalFragmentWhere == null)
{
throw new NotImplementedException();
}
var leftouterjoin = new JoinFragment();
leftouterjoin.JoinType = Metadata.GetOperator(DbExpressionKind.LeftOuterJoin);
leftouterjoin.Name = apply.Name;
// validating that column fragment on the left matches the name
// for the input fragment
var leftColumnFragment = whereleft.Left as ColumnFragment;
if (leftColumnFragment == null)
{
throw new NotImplementedException();
}
if (!leftColumnFragment.TableName.Equals(input.Name))
{
new NotImplementedException();
}
var conditionJoin = new BinaryFragment();
conditionJoin.Left = whereleft.Left;
//update to the new reference
var newColumnFragment = whereright.Right as ColumnFragment;
if (newColumnFragment != null)
{
newColumnFragment.TableName = uf.Name;
}
conditionJoin.Right = newColumnFragment;
conditionJoin.Operator = whereleft.Operator;
leftouterjoin.Condition = conditionJoin;
(uf.Left as SelectStatement).Where = literalFragmentWhere;
(uf.Right as SelectStatement).Where = literalFragmentWhere;
leftouterjoin.Left = input;
leftouterjoin.Right = uf;
return(leftouterjoin);
}
return(select);
}
