public void NormalizeQuerySpecification(QuerySpecification qs)
{
foreach (var sq in qs.EnumerateSubqueries())
{
NormalizeSelectStatement(sq.SelectStatement);
}
// Process join conditions
conditions = new List <LogicalExpressions.Expression>();
var from = qs.FindDescendant <FromClause>();
if (from != null)
{
var tablesource = from.FindDescendant <TableSourceExpression>();
foreach (JoinedTable jt in tablesource.EnumerateDescendantsRecursive <JoinedTable>(typeof(Subquery)))
{
// CROSS JOIN queries have no search condition
SearchCondition sc = jt.FindDescendant <SearchCondition>();
if (sc != null)
{
conditions.Add(GetConjunctiveNormalForm(sc));
}
}
}
// Process where clause
WhereClause where = qs.FindDescendant <WhereClause>();
if (where != null)
{
var sc = where.FindDescendant <SearchCondition>();
conditions.Add(GetConjunctiveNormalForm(sc));
}
}
public void NormalizeQuerySpecification(QuerySpecification qs)
{
foreach (var sq in qs.EnumerateSubqueries())
{
NormalizeSelectStatement(sq.SelectStatement);
}
// Process join conditions
conditions = new List<LogicalExpressions.Expression>();
var from = qs.FindDescendant<FromClause>();
if (from != null)
{
var tablesource = from.FindDescendant<TableSourceExpression>();
foreach (JoinedTable jt in tablesource.EnumerateDescendantsRecursive<JoinedTable>(typeof(Subquery)))
{
// CROSS JOIN queries have no search condition
SearchCondition sc = jt.FindDescendant<SearchCondition>();
if (sc != null)
{
conditions.Add(GetConjunctiveNormalForm(sc));
}
}
}
// Process where clause
WhereClause where = qs.FindDescendant<WhereClause>();
if (where != null)
{
var sc = where.FindDescendant<SearchCondition>();
conditions.Add(GetConjunctiveNormalForm(sc));
}
}
protected void ResolveOrderByClause(OrderByClause orderBy, QuerySpecification firstqs)
{
if (orderBy != null)
{
ResolveTableReferences(firstqs, orderBy);
ResolveColumnReferences(firstqs, orderBy, ColumnContext.OrderBy);
}
}
/// <summary>
/// Collect list of table sources and load columns from the schema.
/// </summary>
/// <remarks>
/// Source tables are put into a dictionary that is keyed by table alias
/// or table name.
/// </remarks>
/// <param name="qs"></param>
private void CollectSourceTableReferences(QuerySpecification qs)
{
// --- Collect column references from subqueries or load from the database schema
foreach (var tr in qs.EnumerateSourceTableReferences(false))
{
string tablekey;
if (tr.IsSubquery || tr.IsComputed || tr.IsUdf || tr.Alias != null)
{
tablekey = tr.Alias;
}
else
{
// If no alias is used then use table name
tablekey = tr.DatabaseObjectName;
}
// Make sure that table key is used only once
if (qs.SourceTableReferences.ContainsKey(tablekey))
{
throw CreateException(ExceptionMessages.DuplicateTableAlias, null, tablekey, tr.Node);
}
else
{
var ntr = new TableReference(tr);
if (!ntr.IsSubquery && !ntr.IsComputed)
{
// Load table description from underlying schema
// Attempt to load dataset and throw exception of name cannot be resolved
DatasetBase ds;
try
{
ds = schemaManager.Datasets[ntr.DatasetName];
}
catch (KeyNotFoundException ex)
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, ex, ntr.DatasetName, ntr.Node);
}
catch (SchemaException ex)
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, ex, ntr.DatasetName, ntr.Node);
}
ntr.DatabaseObject = ds.GetObject(ntr.DatabaseName, ntr.SchemaName, ntr.DatabaseObjectName);
// Load column descriptions for the table
ntr.LoadColumnReferences(schemaManager);
}
qs.SourceTableReferences.Add(tablekey, ntr);
}
}
}
/// <summary>
/// Looks for a * in the select list and throws an exception if there's any
/// </summary>
/// <param name="qs"></param>
protected void ValidateStarInSelectList(QuerySpecification qs)
{
// Look for stars (*) in the select list
foreach (var i in qs.FindDescendant <SelectList>().Nodes)
{
if (i is Mul)
{
throw CreateException(ExceptionMessages.StarColumnNotAllowed, i);
}
}
}
public static SelectList Create(QuerySpecification querySpecification)
{
SelectList root = null;
SelectList last = null;
foreach (var tr in querySpecification.SourceTableReferences.Values)
{
Create(ref root, ref last, tr);
}
return root;
}
public static SelectList Create(QuerySpecification querySpecification)
{
SelectList root = null;
SelectList last = null;
foreach (var tr in querySpecification.SourceTableReferences.Values)
{
Create(ref root, ref last, tr);
}
return(root);
}
private void CopyResultsColumns(QuerySpecification qs)
{
int index = 0;
foreach (var ce in qs.EnumerateSelectListColumnExpressions())
{
var cr = ce.ColumnReference;
cr.SelectListIndex = index++;
qs.ResultsTableReference.ColumnReferences.Add(cr);
}
}
/// <summary>
/// Substitutes dataset and schema defaults into table source table references
/// </summary>
/// <param name="qs"></param>
protected void SubstituteTableAndColumnDefaults(QuerySpecification qs)
{
foreach (var tr in qs.EnumerateSourceTableReferences(false))
{
if (tr.IsTableOrView)
{
tr.SubstituteDefaults(SchemaManager, defaultTableDatasetName);
}
else if (tr.IsUdf)
{
tr.SubstituteDefaults(SchemaManager, defaultFunctionDatasetName);
}
}
}
protected void ValidateColumnExpression(QuerySpecification qs, ColumnExpression ce)
{
// TODO: delete
// eliminate star queries
/*if (ce.ColumnReference.IsStar)
{
throw CreateException(ExceptionMessages.StarColumnNotAllowed, null, null, ce);
}*/
foreach (ColumnIdentifier ci in ce.EnumerateDescendantsRecursive<ColumnIdentifier>(null))
{
ValidateColumnIdentifier(qs, ci);
}
// *** TODO: look for duplicate aliases
}
protected void ValidateColumnExpression(QuerySpecification qs, ColumnExpression ce)
{
// TODO: delete
// eliminate star queries
/*if (ce.ColumnReference.IsStar)
* {
* throw CreateException(ExceptionMessages.StarColumnNotAllowed, null, null, ce);
* }*/
foreach (ColumnIdentifier ci in ce.EnumerateDescendantsRecursive <ColumnIdentifier>(null))
{
ValidateColumnIdentifier(qs, ci);
}
// *** TODO: look for duplicate aliases
}
private void SubstituteStars(QuerySpecification qs, Node node)
{
if (node != null)
{
var n = node.Stack.First;
while (n != null)
{
if (n.Value is SelectList)
{
n.Value = ((SelectList)n.Value).SubstituteStars();
}
n = n.Next;
}
}
}
protected void ValidateQuerySpecification(QuerySpecification qs)
{
// Call recursively for subqueries
#if false
foreach (var sq in qs.EnumerateSubqueries())
{
ValidateQuerySpecification(sq);
}
#endif
ValidateTableReferences(qs);
ValidateStarInSelectList(qs);
// Loop through all column expressions of the select list and try to resolve them
foreach (ColumnExpression ce in qs.FindDescendant <SelectList>().EnumerateDescendants <ColumnExpression>())
{
ValidateColumnExpression(qs, ce);
}
}
/// <summary>
/// Resolves all table references of all nodes below a node,
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
/// <param name="n"></param>
private void ResolveTableReferences(QuerySpecification qs, Node n)
{
foreach (object o in n.Nodes)
{
// Skip the into and clause and subqueries
if (!(o is IntoClause) && !(o is SubqueryTableSource))
{
if (o is Node)
{
ResolveTableReferences(qs, (Node)o); // Recursive call
}
}
}
if (n is ITableReference && ((ITableReference)n).TableReference != null)
{
ResolveTableReference(qs, (ITableReference)n);
}
}
/// <summary>
/// Internal routine to perform the name resolution steps on a single
/// query specification
/// </summary>
/// <param name="qs"></param>
protected void ResolveQuerySpecification(QuerySpecification qs, int depth)
{
// At this point the table and column references are all parsed
// from the query but no name resolution and cross-identification
// of these references have happened yet. After the cross-idenfication
// routine, the same tables and columns will be tagged by the
// same TableReference and ColumnReference instances.
// First of all, call everything recursively for subqueries. Subqueries
// can appear within the table sources and in the where clause semi-join
// expressions
foreach (var sq in qs.EnumerateSubqueries())
{
ResolveSelectStatement(sq.SelectStatement, depth + 1);
}
// Substitute default dataset names and schema names
// This is typically the MYDB and dbo
SubstituteTableAndColumnDefaults(qs);
// Column references will be stored under the query specification
CollectSourceTableReferences(qs);
// Column identifiers can contain table names, aliases or nothing,
// resolve them now
ResolveTableReferences(qs);
// Substitute SELECT * expressions
SubstituteStars(qs);
// Resolve column references of each occurance
ResolveColumnReferences(qs);
// Copy resultset columns to the appropriate collection
CopyResultsColumns(qs);
// Add default aliases to column expressions in the form of tablealias_columnname
if (depth == 0)
{
AssignDefaultColumnAliases(qs);
}
}
/// <summary>
/// Resolves all table references of all nodes below a node,
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
/// <param name="n"></param>
private void ResolveColumnReferences(QuerySpecification qs, Node n, ColumnContext context)
{
context = GetColumnContext(n, context);
foreach (object o in n.Nodes)
{
// Skip the into and clause and subqueries
if (!(o is IntoClause) && !(o is SubqueryTableSource))
{
if (o is Node)
{
ResolveColumnReferences(qs, (Node)o, context); // Recursive call
}
}
}
if (n is IColumnReference)
{
ResolveColumnReference(qs, (IColumnReference)n, context);
}
}
protected void ValidateColumnIdentifier(QuerySpecification qs, ColumnIdentifier ci)
{
// TODO: modify to look for stars inside expressions
/*
* if (ci.ColumnReference.IsStar)
* {
* // Check if it's a count(*), that's the only expression allowed to
* // contain a *
* var fc = ci.FindAscendant<FunctionCall>();
* if (fc != null)
* {
* var fn = fc.FindDescendantRecursive<FunctionName>();
* if (fn != null && SqlParser.ComparerInstance.Compare(fn.Value, "COUNT") == 0)
* {
* return;
* }
* }
*
* throw CreateException(ExceptionMessages.StarColumnNotAllowed, null, null, ci);
* }*/
}
/// <summary>
/// Adds default aliases to columns with no aliases specified in the query
/// </summary>
/// <param name="qs"></param>
protected void AssignDefaultColumnAliases(QuerySpecification qs)
{
var aliases = new HashSet <string>(SchemaManager.Comparer);
foreach (var ce in qs.EnumerateSelectListColumnExpressions())
{
var cr = ce.ColumnReference;
string alias;
if (cr.ColumnAlias == null)
{
if (cr.ColumnName == null)
{
alias = GetUniqueColumnAlias(aliases, String.Format("Col_{0}", cr.SelectListIndex));
}
else
{
if (cr.TableReference != null && cr.TableReference.Alias != null)
{
alias = GetUniqueColumnAlias(aliases, String.Format("{0}_{1}", cr.TableReference.Alias, cr.ColumnName));
}
else
{
alias = GetUniqueColumnAlias(aliases, cr.ColumnName);
}
}
}
else
{
// Alias is set explicitly, so do not make it unique forcibly
alias = cr.ColumnAlias;
}
aliases.Add(alias);
cr.ColumnAlias = alias;
}
}
protected void ValidateTableReferences(QuerySpecification qs)
{
#if false
foreach (var ats in qs.EnumerateTableSources(false))
{
var ts = ats.FindDescendant <SimpleTableSource>();
if (ts != null)
{
TableReference tr = ts.TableReference;
// Make sure no database name specified -> invalid in skyquery
if (tr.DatabaseName != null)
{
throw CreateException(ExceptionMessages.DatabaseNameNotAllowed, null, tr.DatabaseName, ts);
}
return;
}
throw new NotImplementedException();
}
#endif
}
private void CopyResultsColumns(QuerySpecification qs)
{
int index = 0;
foreach (var ce in qs.EnumerateSelectListColumnExpressions())
{
var cr = ce.ColumnReference;
cr.SelectListIndex = index++;
qs.ResultsTableReference.ColumnReferences.Add(cr);
}
}
/// <summary>
/// Replace SELECT * and SELECT alias.* with explicit column lists
/// </summary>
/// <param name="qs"></param>
private void SubstituteStars(QuerySpecification qs)
{
SubstituteStars(qs, qs);
}
/// <summary>
/// Resolves the table references of all nodes below a query specification
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
private void ResolveTableReferences(QuerySpecification qs)
{
ResolveTableReferences(qs, (Node)qs);
}
/// <summary>
/// Resolves all table references of all nodes below a node,
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
/// <param name="n"></param>
private void ResolveColumnReferences(QuerySpecification qs, Node n, ColumnContext context)
{
context = GetColumnContext(n, context);
foreach (object o in n.Nodes)
{
// Skip the into and clause and subqueries
if (!(o is IntoClause) && !(o is SubqueryTableSource))
{
if (o is Node)
{
ResolveColumnReferences(qs, (Node)o, context); // Recursive call
}
}
}
if (n is IColumnReference)
{
ResolveColumnReference(qs, (IColumnReference)n, context);
}
}
private void CopyMembers(QuerySpecification old)
{
this.sourceTableReferences = new Dictionary<string, TableReference>(old.sourceTableReferences);
this.resultsTableReference = new TableReference(old.resultsTableReference);
}
/// <summary>
/// Looks for a * in the select list and throws an exception if there's any
/// </summary>
/// <param name="qs"></param>
protected void ValidateStarInSelectList(QuerySpecification qs)
{
// Look for stars (*) in the select list
foreach (var i in qs.FindDescendant<SelectList>().Nodes)
{
if (i is Mul)
{
throw CreateException(ExceptionMessages.StarColumnNotAllowed, i);
}
}
}
protected void ValidateTableReferences(QuerySpecification qs)
{
#if false
foreach (var ats in qs.EnumerateTableSources(false))
{
var ts = ats.FindDescendant<SimpleTableSource>();
if (ts != null)
{
TableReference tr = ts.TableReference;
// Make sure no database name specified -> invalid in skyquery
if (tr.DatabaseName != null)
{
throw CreateException(ExceptionMessages.DatabaseNameNotAllowed, null, tr.DatabaseName, ts);
}
return;
}
throw new NotImplementedException();
}
#endif
}
protected void ValidateQuerySpecification(QuerySpecification qs)
{
// Call recursively for subqueries
#if false
foreach (var sq in qs.EnumerateSubqueries())
{
ValidateQuerySpecification(sq);
}
#endif
ValidateTableReferences(qs);
ValidateStarInSelectList(qs);
// Loop through all column expressions of the select list and try to resolve them
foreach (ColumnExpression ce in qs.FindDescendant<SelectList>().EnumerateDescendants<ColumnExpression>())
{
ValidateColumnExpression(qs, ce);
}
}
public TableReference(QuerySpecification qs)
{
InitializeMembers();
this.Node = qs;
}
private void ResolveColumnReference(QuerySpecification qs, IColumnReference cr, ColumnContext context)
{
// Try to resolve the table belonging to a column based solely on
// column name. This function is called only on column references with
// unspecified table parts.
// Star columns cannot be resolved, treat them separately
if (!cr.ColumnReference.IsStar && !cr.ColumnReference.IsComplexExpression)
{
ColumnReference ncr = null;
int q = 0;
if (cr.ColumnReference.TableReference.IsUndefined)
{
// This has an empty table reference (only column name specified)
// Look for a match based on column name only
foreach (var tr in qs.SourceTableReferences.Values)
{
foreach (var ccr in tr.ColumnReferences)
{
if (cr.ColumnReference.Compare(ccr))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
ncr = ccr;
q++;
}
}
}
}
else if (!cr.ColumnReference.TableReference.IsUndefined)
{
foreach (var ccr in cr.ColumnReference.TableReference.ColumnReferences)
{
if (cr.ColumnReference.Compare(ccr))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
ncr = ccr;
q++;
}
}
}
if (q == 0)
{
throw CreateException(ExceptionMessages.UnresolvableColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
// Make copy here and preserve alias!
ncr.ColumnContext |= context;
ncr = new ColumnReference(ncr);
if (cr.ColumnReference != null && cr.ColumnReference.ColumnAlias != null)
{
ncr.ColumnAlias = cr.ColumnReference.ColumnAlias;
}
cr.ColumnReference = ncr;
}
}
private void ResolveColumnReference(QuerySpecification qs, IColumnReference cr, ColumnContext context)
{
// Try to resolve the table belonging to a column based solely on
// column name. This function is called only on column references with
// unspecified table parts.
// Star columns cannot be resolved, treat them separately
if (!cr.ColumnReference.IsStar && !cr.ColumnReference.IsComplexExpression)
{
ColumnReference ncr = null;
int q = 0;
if (cr.ColumnReference.TableReference.IsUndefined)
{
// This has an empty table reference (only column name specified)
// Look for a match based on column name only
foreach (var tr in qs.SourceTableReferences.Values)
{
foreach (var ccr in tr.ColumnReferences)
{
if (cr.ColumnReference.Compare(ccr))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
ncr = ccr;
q++;
}
}
}
}
else if (!cr.ColumnReference.TableReference.IsUndefined)
{
foreach (var ccr in cr.ColumnReference.TableReference.ColumnReferences)
{
if (cr.ColumnReference.Compare(ccr))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
ncr = ccr;
q++;
}
}
}
if (q == 0)
{
throw CreateException(ExceptionMessages.UnresolvableColumnReference, null, cr.ColumnReference.ColumnName, (Node)cr);
}
// Make copy here and preserve alias!
ncr.ColumnContext |= context;
ncr = new ColumnReference(ncr);
if (cr.ColumnReference != null && cr.ColumnReference.ColumnAlias != null)
{
ncr.ColumnAlias = cr.ColumnReference.ColumnAlias;
}
cr.ColumnReference = ncr;
}
}
private void CopyMembers(QuerySpecification old)
{
this.sourceTableReferences = new Dictionary <string, TableReference>(old.sourceTableReferences);
this.resultsTableReference = new TableReference(old.resultsTableReference);
}
private void ResolveColumnReferences(QuerySpecification qs)
{
ResolveColumnReferences(qs, (Node)qs, ColumnContext.None);
}
private void ResolveColumnReferences(QuerySpecification qs)
{
ResolveColumnReferences(qs, (Node)qs, ColumnContext.None);
}
/// <summary>
/// Resolves a table reference to a table listed in SourceTableReferences
/// </summary>
/// <param name="qs"></param>
/// <param name="tr"></param>
private void ResolveTableReference(QuerySpecification qs, ITableReference node)
{
// Try to resolve the table alias part of a table reference
// If and alias or table name is specified, this can be done based on
// the already collected table sources.
// If no table or alias is specified and the current node is a column reference,
// where the column is not a complex expression, resolution might be successful by
// column name only.
if (!node.TableReference.IsUndefined)
{
TableReference ntr = null;
string alias = null;
if (node.TableReference.Alias != null)
{
// if table alias found explicitly
alias = node.TableReference.Alias;
}
else if (node.TableReference.DatasetName == null &&
node.TableReference.DatabaseName == null &&
node.TableReference.SchemaName == null &&
node.TableReference.DatabaseObjectName != null &&
qs.SourceTableReferences.ContainsKey(node.TableReference.DatabaseObjectName))
{
// if only table name found and that's an alias
alias = node.TableReference.DatabaseObjectName;
}
if (alias != null)
{
ntr = qs.SourceTableReferences[alias];
}
else
{
// Check if dataset specified and make sure it's valid
if (node.TableReference.DatasetName != null)
{
if (!schemaManager.Datasets.ContainsKey(node.TableReference.DatasetName))
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, null, node.TableReference.DatasetName, (Node)node);
}
}
// if only a table name found and that's not an alias -> must be a table
int q = 0;
foreach (var key in qs.SourceTableReferences.Keys)
{
var tr = qs.SourceTableReferences[key];
if (tr.Compare(node.TableReference))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousTableReference, null, node.TableReference.DatabaseObjectName, (Node)node);
}
ntr = tr;
q++;
}
}
}
if (ntr == null)
{
throw CreateException(ExceptionMessages.UnresolvableTableReference, null, node.TableReference.DatabaseObjectName, (Node)node);
}
node.TableReference = ntr;
}
}
private void AppendPartitioningConditions(QuerySpecification qs, SimpleTableSource ts)
{
if (!double.IsInfinity(PartitioningKeyFrom) || !double.IsInfinity(PartitioningKeyTo))
{
var cg = new SqlServerCodeGenerator();
string format;
if (double.IsInfinity(PartitioningKeyFrom) && double.IsInfinity(PartitioningKeyTo))
{
format = "{1} <= {0} AND {0} < {2}";
}
else if (double.IsInfinity(PartitioningKeyFrom))
{
format = "{0} < {2}";
}
else
{
format = "{1} <= {0}";
}
string sql = String.Format(format,
cg.GetResolvedColumnName(ts.PartitioningColumnReference),
PartitioningKeyFrom.ToString(System.Globalization.CultureInfo.InvariantCulture),
PartitioningKeyTo.ToString(System.Globalization.CultureInfo.InvariantCulture));
var parser = new Jhu.Graywulf.SqlParser.SqlParser();
var sc = (SearchCondition)parser.Execute(new SearchCondition(), sql);
var where = qs.FindDescendant<WhereClause>();
if (where == null)
{
where = WhereClause.Create(sc);
var ws = Whitespace.Create();
var wsn = qs.Stack.AddAfter(qs.Stack.Find(qs.FindDescendant<FromClause>()), ws);
qs.Stack.AddAfter(wsn, where);
}
else
{
where.AppendCondition(sc, "AND");
}
}
// --- remove partition clause
ts.Stack.Remove(ts.FindDescendant<TablePartitionClause>());
}
/// <summary>
/// Resolves all table references of all nodes below a node,
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
/// <param name="n"></param>
private void ResolveTableReferences(QuerySpecification qs, Node n)
{
foreach (object o in n.Nodes)
{
// Skip the into and clause and subqueries
if (!(o is IntoClause) && !(o is SubqueryTableSource))
{
if (o is Node)
{
ResolveTableReferences(qs, (Node)o); // Recursive call
}
}
}
if (n is ITableReference && ((ITableReference)n).TableReference != null)
{
ResolveTableReference(qs, (ITableReference)n);
}
}
/// <summary>
/// Resolves the table references of all nodes below a query specification
/// not descending into subqueries
/// </summary>
/// <param name="qs"></param>
private void ResolveTableReferences(QuerySpecification qs)
{
ResolveTableReferences(qs, (Node)qs);
}
private void SubstituteStars(QuerySpecification qs, Node node)
{
if (node != null)
{
var n = node.Stack.First;
while (n != null)
{
if (n.Value is SelectList)
{
n.Value = ((SelectList)n.Value).SubstituteStars();
}
n = n.Next;
}
}
}
/// <summary>
/// Substitutes dataset and schema defaults into table source table references
/// </summary>
/// <param name="qs"></param>
protected void SubstituteDefaults(QuerySpecification qs)
{
foreach (var tr in qs.EnumerateSourceTableReferences(false))
{
if (tr.IsTableOrView)
{
tr.SubstituteDefaults(SchemaManager, defaultTableDatasetName);
}
else if (tr.IsUdf)
{
tr.SubstituteDefaults(SchemaManager, defaultFunctionDatasetName);
}
}
}
/// <summary>
/// Resolves a table reference to a table listed in SourceTableReferences
/// </summary>
/// <param name="qs"></param>
/// <param name="tr"></param>
private void ResolveTableReference(QuerySpecification qs, ITableReference node)
{
// Try to resolve the table alias part of a table reference
// If and alias or table name is specified, this can be done based on
// the already collected table sources.
// If no table or alias is specified and the current node is a column reference,
// where the column is not a complex expression, resolution might be successful by
// column name only.
if (!node.TableReference.IsUndefined)
{
TableReference ntr = null;
string alias = null;
if (node.TableReference.Alias != null)
{
// if table alias found explicitly
alias = node.TableReference.Alias;
}
else if (node.TableReference.DatasetName == null &&
node.TableReference.DatabaseName == null &&
node.TableReference.SchemaName == null &&
node.TableReference.DatabaseObjectName != null &&
qs.SourceTableReferences.ContainsKey(node.TableReference.DatabaseObjectName))
{
// if only table name found and that's an alias
alias = node.TableReference.DatabaseObjectName;
}
if (alias != null)
{
ntr = qs.SourceTableReferences[alias];
}
else
{
// Check if dataset specified and make sure it's valid
if (node.TableReference.DatasetName != null)
{
if (!schemaManager.Datasets.ContainsKey(node.TableReference.DatasetName))
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, null, node.TableReference.DatasetName, (Node)node);
}
}
// if only a table name found and that's not an alias -> must be a table
int q = 0;
foreach (var tr in qs.SourceTableReferences.Values)
{
if (tr.Compare(node.TableReference))
{
if (q != 0)
{
throw CreateException(ExceptionMessages.AmbigousTableReference, null, node.TableReference.DatabaseObjectName, (Node)node);
}
ntr = tr;
q++;
}
}
}
if (ntr == null)
{
throw CreateException(ExceptionMessages.UnresolvableTableReference, null, node.TableReference.DatabaseObjectName, (Node)node);
}
node.TableReference = ntr;
}
}
/// <summary>
/// Collect list of table sources and load columns from the schema.
/// </summary>
/// <remarks>
/// Source tables are put into a dictionary that is keyed by table alias
/// or table name.
/// </remarks>
/// <param name="qs"></param>
private void CollectSourceTableReferences(QuerySpecification qs)
{
// --- Collect column references from subqueries or load from the database schema
foreach (var tr in qs.EnumerateSourceTableReferences(false))
{
string tablekey;
if (tr.IsSubquery || tr.IsComputed || tr.IsUdf || tr.Alias != null)
{
tablekey = tr.Alias;
}
else
{
// If no alias is used then use table name
tablekey = tr.DatabaseObjectName;
}
// Make sure that table key is used only once
if (qs.SourceTableReferences.ContainsKey(tablekey))
{
throw CreateException(ExceptionMessages.DuplicateTableAlias, null, tablekey, tr.Node);
}
else
{
var ntr = new TableReference(tr);
if (!ntr.IsSubquery && !ntr.IsComputed)
{
// Load table description from underlying schema
// Attempt to load dataset and throw exception of name cannot be resolved
DatasetBase ds;
try
{
ds = schemaManager.Datasets[ntr.DatasetName];
}
catch (KeyNotFoundException ex)
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, ex, ntr.DatasetName, ntr.Node);
}
catch (SchemaException ex)
{
throw CreateException(ExceptionMessages.UnresolvableDatasetReference, ex, ntr.DatasetName, ntr.Node);
}
ntr.DatabaseObject = ds.GetObject(ntr.DatabaseName, ntr.SchemaName, ntr.DatabaseObjectName);
// Load column descriptions for the table
ntr.LoadColumnReferences(schemaManager);
}
qs.SourceTableReferences.Add(tablekey, ntr);
}
}
}
/// <summary>
/// Adds default aliases to columns with no aliases specified in the query
/// </summary>
/// <param name="qs"></param>
protected void AssignDefaultColumnAliases(QuerySpecification qs)
{
var aliases = new HashSet<string>(SchemaManager.Comparer);
foreach (var ce in qs.EnumerateSelectListColumnExpressions())
{
var cr = ce.ColumnReference;
string alias;
if (cr.ColumnAlias == null)
{
if (cr.ColumnName == null)
{
alias = GetUniqueColumnAlias(aliases, String.Format("Col_{0}", cr.SelectListIndex));
}
else
{
if (cr.TableReference != null && cr.TableReference.Alias != null)
{
alias = GetUniqueColumnAlias(aliases, String.Format("{0}_{1}", cr.TableReference.Alias, cr.ColumnName));
}
else
{
alias = GetUniqueColumnAlias(aliases, cr.ColumnName);
}
}
}
else
{
// Alias is set explicitly, so do not make it unique forcibly
alias = cr.ColumnAlias;
}
aliases.Add(alias);
cr.ColumnAlias = alias;
}
}
/// <summary>
/// Replace SELECT * and SELECT alias.* with explicit column lists
/// </summary>
/// <param name="qs"></param>
private void SubstituteStars(QuerySpecification qs)
{
SubstituteStars(qs, qs);
}
public TableReference(QuerySpecification qs)
{
InitializeMembers();
this.node = qs;
}
protected void ResolveOrderByClause(OrderByClause orderBy, QuerySpecification firstqs)
{
if (orderBy != null)
{
ResolveTableReferences(firstqs, orderBy);
ResolveColumnReferences(firstqs, orderBy, ColumnContext.OrderBy);
}
}
protected void ValidateColumnIdentifier(QuerySpecification qs, ColumnIdentifier ci)
{
// TODO: modify to look for stars inside expressions
/*
if (ci.ColumnReference.IsStar)
{
// Check if it's a count(*), that's the only expression allowed to
// contain a *
var fc = ci.FindAscendant<FunctionCall>();
if (fc != null)
{
var fn = fc.FindDescendantRecursive<FunctionName>();
if (fn != null && SqlParser.ComparerInstance.Compare(fn.Value, "COUNT") == 0)
{
return;
}
}
throw CreateException(ExceptionMessages.StarColumnNotAllowed, null, null, ci);
}*/
}
/// <summary>
/// Internal routine to perform the name resolution steps on a single
/// query specification
/// </summary>
/// <param name="qs"></param>
protected void ResolveQuerySpecification(QuerySpecification qs, int depth)
{
// At this point the table and column references are all parsed
// from the query but no name resolution and cross-identification
// of these references have happened yet. After the cross-idenfication
// routine, the same tables and columns will be tagged by the
// same TableReference and ColumnReference instances.
// First of all, call everything recursively for subqueries. Subqueries
// can appear within the table sources and in the where clause semi-join
// expressions
foreach (var sq in qs.EnumerateSubqueries())
{
ResolveSelectStatement(sq.SelectStatement, depth + 1);
}
// Substitute default dataset names and schema names
// This is typically the MYDB and dbo
SubstituteDefaults(qs);
// Column references will be stored under the query specification
CollectSourceTableReferences(qs);
// Column identifiers can contain table names, aliases or nothing,
// resolve them now
ResolveTableReferences(qs);
// Substitute SELECT * expressions
SubstituteStars(qs);
// Resolve column references of each occurance
ResolveColumnReferences(qs);
// Copy resultset columns to the appropriate collection
CopyResultsColumns(qs);
// Add default aliases to column expressions in the form of tablealias_columnname
if (depth == 0)
{
AssignDefaultColumnAliases(qs);
}
}
public QuerySpecification(QuerySpecification old)
: base(old)
{
CopyMembers(old);
}
public QuerySpecification(QuerySpecification old)
: base(old)
{
CopyMembers(old);
}