private void GatherUnionExpressions(SqlNode node, List <SqlExpression> exprs)
{
SqlUnion union = node as SqlUnion;
if (union != null)
{
this.GatherUnionExpressions(union.Left, exprs);
this.GatherUnionExpressions(union.Right, exprs);
}
else
{
SqlSelect sel = node as SqlSelect;
if (sel != null)
{
SqlAliasRef aref = sel.Selection as SqlAliasRef;
if (aref != null)
{
this.GatherUnionExpressions(aref.Alias.Node, exprs);
}
else
{
exprs.Add(sel.Selection);
}
}
}
}
internal override SqlNode VisitUnion(SqlUnion su)
{
bool changedLeft = false;
bool containsLongExpressionsLeft = false;
SqlSelect left = su.Left as SqlSelect;
if (left != null)
{
ConvertColumnsToMax(left, out changedLeft, out containsLongExpressionsLeft);
}
bool changedRight = false;
bool containsLongExpressionsRight = false;
SqlSelect right = su.Right as SqlSelect;
if (right != null)
{
ConvertColumnsToMax(right, out changedRight, out containsLongExpressionsRight);
}
if (!su.All && (containsLongExpressionsLeft || containsLongExpressionsRight))
{
// unless the UNION is 'ALL', the server will perform a DISTINCT operation,
// which isn't valid for large types (text, ntext, image)
this.annotations.Add(su, new SqlServerCompatibilityAnnotation(
Strings.TextNTextAndImageCannotOccurInUnion(su.SourceExpression), SqlProvider.ProviderMode.Sql2000, SqlProvider.ProviderMode.SqlCE));
}
return(base.VisitUnion(su));
}
internal override SqlExpression VisitAliasRef(SqlAliasRef aref)
{
SqlNode node = aref.Alias.Node;
if (node is SqlTable || node is SqlTableValuedFunctionCall)
{
return(aref);
}
SqlUnion union = node as SqlUnion;
if (union != null)
{
return(this.ExpandUnion(union));
}
SqlSelect ss = node as SqlSelect;
if (ss != null)
{
return(this.VisitExpression(ss.Selection));
}
SqlExpression exp = node as SqlExpression;
if (exp != null)
{
return(this.VisitExpression(exp));
}
throw Error.CouldNotHandleAliasRef(node.NodeType);
}
internal override SqlNode VisitUnion(SqlUnion su)
{
bool saveForceReferenceAll = this.forceReferenceAll;
this.forceReferenceAll = true;
su.Left = this.Visit(su.Left);
su.Right = this.Visit(su.Right);
this.forceReferenceAll = saveForceReferenceAll;
return(su);
}
internal override SqlNode VisitUnion(SqlUnion su)
{
Scope save = this.current;
this.current = null;
SqlNode result = base.VisitUnion(su);
this.current = save;
return(result);
}
private SqlExpression ExpandUnion(SqlUnion union)
{
List <SqlExpression> exprs = new List <SqlExpression>(2);
this.GatherUnionExpressions(union, exprs);
this.sourceExpression = union.SourceExpression;
SqlExpression result = this.ExpandTogether(exprs);
return(result);
}
internal override SqlNode VisitUnion(SqlUnion su)
{
// ordering does not carry through a union
this.orders = null;
su.Left = this.Visit(su.Left);
this.orders = null;
su.Right = this.Visit(su.Right);
this.orders = null;
return(su);
}
private SqlUnion GetUnion(SqlSource source)
{
SqlAlias alias = source as SqlAlias;
if (alias != null)
{
SqlUnion union = alias.Node as SqlUnion;
if (union != null)
{
return(union);
}
}
return(null);
}
internal override SqlSelect VisitSelect(SqlSelect select)
{
base.VisitSelect(select);
// enforce exact ordering of columns in union selects
SqlUnion union = this.GetUnion(select.From);
if (union != null)
{
SqlSelect sleft = union.Left as SqlSelect;
SqlSelect sright = union.Right as SqlSelect;
if (sleft != null & sright != null)
{
// preset ordinals to high values (so any unreachable column definition is ordered last)
for (int i = 0, n = sleft.Row.Columns.Count; i < n; i++)
{
sleft.Row.Columns[i].Ordinal = select.Row.Columns.Count + i;
}
for (int i = 0, n = sright.Row.Columns.Count; i < n; i++)
{
sright.Row.Columns[i].Ordinal = select.Row.Columns.Count + i;
}
// next assign ordinals to all direct columns in subselects
for (int i = 0, n = select.Row.Columns.Count; i < n; i++)
{
SqlExprSet es = select.Row.Columns[i].Expression as SqlExprSet;
if (es != null)
{
for (int e = 0, en = es.Expressions.Count; e < en; e++)
{
SqlColumnRef cr = es.Expressions[e] as SqlColumnRef;
if (cr != null && e >= select.Row.Columns.Count)
{
cr.Column.Ordinal = i;
}
}
}
}
// next sort columns in left & right subselects
Comparison <SqlColumn> comp = (x, y) => x.Ordinal - y.Ordinal;
sleft.Row.Columns.Sort(comp);
sright.Row.Columns.Sort(comp);
}
}
return(select);
}
internal virtual SqlNode VisitUnion(SqlUnion su)
{
su.Left = this.Visit(su.Left);
su.Right = this.Visit(su.Right);
return(su);
}
internal override SqlNode VisitUnion(SqlUnion su)
{
return(new SqlUnion(this.Visit(su.Left), this.Visit(su.Right), su.All));
}
internal override SqlNode VisitUnion(SqlUnion su)
{
this.canJoin = false;
return(base.VisitUnion(su));
}
internal override SqlNode VisitUnion(SqlUnion su)
{
return(su);
}
internal override SqlNode VisitUnion(SqlUnion su) => new SqlUnion(Visit(su.Left), Visit(su.Right), su.All);
