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Updated error messages to match SQL Server
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@MarkMpn
MarkMpn committed Sep 5, 2023
1 parent b588229 commit f0a8915
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Showing 2 changed files with 176 additions and 13 deletions.
154 changes: 154 additions & 0 deletions MarkMpn.Sql4Cds.Engine.Tests/CteTests.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,160 @@ WITH cte AS (SELECT contactid, firstname, lastname FROM contact WHERE firstname
}
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void MultipleRecursiveReferences()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT cte.* FROM cte a INNER JOIN cte b ON a.lastname = b.lastname
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void HintsOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT cte.* FROM cte WITH (NOLOCK)
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void RecursionWithoutUnionAll()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION
SELECT cte.* FROM cte
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void OrderByWithoutTop()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT cte.* FROM cte
ORDER BY firstname
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void GroupByOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT cte.* FROM cte GROUP BY contactid, firstname, lastname
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void AggregateOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT MIN(contactid), MIN(firstname), MIN(lastname) FROM cte
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void TopOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT TOP 10 cte.* FROM cte
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void OuterJoinOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT cte.* FROM contact LEFT OUTER JOIN cte ON contact.lastname = cte.lastname
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

[TestMethod]
[ExpectedException(typeof(NotSupportedQueryFragmentException))]
public void SubqueryOnRecursiveReference()
{
var planBuilder = new ExecutionPlanBuilder(_localDataSource.Values, this);

var query = @"
WITH cte AS (
SELECT contactid, firstname, lastname FROM contact WHERE firstname = 'Mark'
UNION ALL
SELECT contactid, firstname, lastname FROM contact WHERE lastname IN (SELECT lastname FROM cte)
)
SELECT * FROM cte";

planBuilder.Build(query, null, out _);
}

private T AssertNode<T>(IExecutionPlanNode node) where T : IExecutionPlanNode
{
Assert.IsInstanceOfType(node, typeof(T));
Expand Down
35 changes: 22 additions & 13 deletions MarkMpn.Sql4Cds.Engine/Visitors/CteValidatorVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ public override void Visit(FromClause node)

// The FROM clause of a recursive member must refer only one time to the CTE expression_name.
if (_cteReferenceCount > 1)
throw new NotSupportedQueryFragmentException("Recursive CTEs can only be referenced once", node);
throw new NotSupportedQueryFragmentException($"Recursive member of a common table expression '{Name}' has multiple recursive references.", node);
}

public override void Visit(NamedTableReference node)
Expand All @@ -51,7 +51,7 @@ public override void Visit(NamedTableReference node)
// The following items aren't allowed in the CTE_query_definition of a recursive member:
// A hint applied to a recursive reference to a CTE inside a CTE_query_definition.
if (node.TableHints.Count > 0)
throw new NotSupportedQueryFragmentException("Table hints are not supported in CTEs", node.TableHints[0]);
throw new NotSupportedQueryFragmentException($"Hints are not allowed on recursive common table expression (CTE) references. Consider removing hint from recursive CTE reference '{node.SchemaObject.ToSql()}'.", node.TableHints[0]);
}

base.Visit(node);
Expand All @@ -71,7 +71,7 @@ public override void ExplicitVisit(BinaryQueryExpression node)

// UNION ALL is the only set operator allowed between the last anchor member and first recursive member, and when combining multiple recursive members.
if (IsRecursive && (node.BinaryQueryExpressionType != BinaryQueryExpressionType.Union || !node.All))
throw new NotSupportedQueryFragmentException("Recursive CTEs must have a UNION ALL between the anchor and recursive parts", node);
throw new NotSupportedQueryFragmentException($"Recursive common table expression '{Name}' does not contain a top-level UNION ALL operator", node);
}

public override void Visit(QuerySpecification node)
Expand All @@ -85,44 +85,44 @@ public override void Visit(QuerySpecification node)
// The following clauses can't be used in the CTE_query_definition:
// ORDER BY (except when a TOP clause is specified)
if (node.OrderByClause != null && node.TopRowFilter == null)
throw new NotSupportedQueryFragmentException("ORDER BY is not supported in CTEs", node.OrderByClause);
throw new NotSupportedQueryFragmentException("The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified", node.OrderByClause);

// FOR BROWSE
if (node.ForClause is BrowseForClause)
throw new NotSupportedQueryFragmentException("FOR BROWSE is not supported in CTEs", node.ForClause);
throw new NotSupportedQueryFragmentException("The FOR BROWSE clause is no longer supported in views", node.ForClause);

if (IsRecursive)
{
// The following items aren't allowed in the CTE_query_definition of a recursive member:
// SELECT DISTINCT
if (node.UniqueRowFilter == UniqueRowFilter.Distinct)
throw new NotSupportedQueryFragmentException("DISTINCT is not supported in CTEs", node);
throw new NotSupportedQueryFragmentException($"DISTINCT operator is not allowed in the recursive part of a recursive common table expression '{Name}'.", node);

// GROUP BY
if (node.GroupByClause != null)
throw new NotSupportedQueryFragmentException("GROUP BY is not supported in CTEs", node.GroupByClause);
throw new NotSupportedQueryFragmentException($"GROUP BY, HAVING, or aggregate functions are not allowed in the recursive part of a recursive common table expression '{Name}'", node.GroupByClause);

// TODO: PIVOT

// HAVING
if (node.HavingClause != null)
throw new NotSupportedQueryFragmentException("HAVING is not supported in CTEs", node.HavingClause);
throw new NotSupportedQueryFragmentException($"GROUP BY, HAVING, or aggregate functions are not allowed in the recursive part of a recursive common table expression '{Name}'", node.HavingClause);

// Scalar aggregation
if (_scalarAggregate != null)
throw new NotSupportedQueryFragmentException("Scalar aggregation is not supported in CTEs", _scalarAggregate);
throw new NotSupportedQueryFragmentException($"GROUP BY, HAVING, or aggregate functions are not allowed in the recursive part of a recursive common table expression '{Name}'", _scalarAggregate);

// TOP
if (node.TopRowFilter != null)
throw new NotSupportedQueryFragmentException("TOP is not supported in CTEs", node.TopRowFilter);
if (node.TopRowFilter != null || node.OffsetClause != null)
throw new NotSupportedQueryFragmentException($"The TOP or OFFSET operator is not allowed in the recursive part of a recursive common table expression '{Name}'", (TSqlFragment)node.TopRowFilter ?? node.OffsetClause);

// LEFT, RIGHT, OUTER JOIN (INNER JOIN is allowed)
if (_outerJoin != null)
throw new NotSupportedQueryFragmentException("Outer joins are not supported in CTEs", _outerJoin);
throw new NotSupportedQueryFragmentException($"Outer join is not allowed in the recursive part of a recursive common table expression '{Name}'", _outerJoin);

// Subqueries
if (_subquery != null)
throw new NotSupportedQueryFragmentException("Subqueries are not supported in CTEs", _subquery);
throw new NotSupportedQueryFragmentException("Recursive references are not allowed in subqueries", _subquery);
}
}

Expand All @@ -138,7 +138,16 @@ public override void Visit(SelectStatement node)
// OPTION clause with query hints
if (node.OptimizerHints.Count > 0)
throw new NotSupportedQueryFragmentException("Optimizer hints are not supported in CTEs", node.OptimizerHints[0]);
}

public override void ExplicitVisit(ScalarSubquery node)
{
var count = _cteReferenceCount;

base.ExplicitVisit(node);

if (_cteReferenceCount > count)
_subquery = node;
}
}
}

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