309 lines
11 KiB
C#
309 lines
11 KiB
C#
|
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
|
|||
|
|
using System;
|
|||
|
|
using System.Collections.Generic;
|
|||
|
|
using System.Diagnostics;
|
|||
|
|
using System.IO;
|
|||
|
|
using System.Text;
|
|||
|
|
using System.Data.SqlClient;
|
|||
|
|
using System.Data.Metadata.Edm;
|
|||
|
|
using System.Data.Common.CommandTrees;
|
|||
|
|
|
|||
|
|
namespace SampleEntityFrameworkProvider
|
|||
|
|
{
|
|||
|
|
/// <summary>
|
|||
|
|
/// A SqlSelectStatement represents a canonical SQL SELECT statement.
|
|||
|
|
/// It has fields for the 5 main clauses
|
|||
|
|
/// <list type="number">
|
|||
|
|
/// <item>SELECT</item>
|
|||
|
|
/// <item>FROM</item>
|
|||
|
|
/// <item>WHERE</item>
|
|||
|
|
/// <item>GROUP BY</item>
|
|||
|
|
/// <item>ORDER BY</item>
|
|||
|
|
/// </list>
|
|||
|
|
/// We do not have HAVING, since it does not correspond to anything in the DbCommandTree.
|
|||
|
|
/// Each of the fields is a SqlBuilder, so we can keep appending SQL strings
|
|||
|
|
/// or other fragments to build up the clause.
|
|||
|
|
///
|
|||
|
|
/// We have a IsDistinct property to indicate that we want distict columns.
|
|||
|
|
/// This is given out of band, since the input expression to the select clause
|
|||
|
|
/// may already have some columns projected out, and we use append-only SqlBuilders.
|
|||
|
|
/// The DISTINCT is inserted when we finally write the object into a string.
|
|||
|
|
///
|
|||
|
|
/// Also, we have a Top property, which is non-null if the number of results should
|
|||
|
|
/// be limited to certain number. It is given out of band for the same reasons as DISTINCT.
|
|||
|
|
///
|
|||
|
|
/// The FromExtents contains the list of inputs in use for the select statement.
|
|||
|
|
/// There is usually just one element in this - Select statements for joins may
|
|||
|
|
/// temporarily have more than one.
|
|||
|
|
///
|
|||
|
|
/// If the select statement is created by a Join node, we maintain a list of
|
|||
|
|
/// all the extents that have been flattened in the join in AllJoinExtents
|
|||
|
|
/// <example>
|
|||
|
|
/// in J(j1= J(a,b), c)
|
|||
|
|
/// FromExtents has 2 nodes JoinSymbol(name=j1, ...) and Symbol(name=c)
|
|||
|
|
/// AllJoinExtents has 3 nodes Symbol(name=a), Symbol(name=b), Symbol(name=c)
|
|||
|
|
/// </example>
|
|||
|
|
///
|
|||
|
|
/// If any expression in the non-FROM clause refers to an extent in a higher scope,
|
|||
|
|
/// we add that extent to the OuterExtents list. This list denotes the list
|
|||
|
|
/// of extent aliases that may collide with the aliases used in this select statement.
|
|||
|
|
/// It is set by <see cref="SqlGenerator.Visit(DbVariableReferenceExpression)"/>.
|
|||
|
|
/// An extent is an outer extent if it is not one of the FromExtents.
|
|||
|
|
///
|
|||
|
|
///
|
|||
|
|
/// </summary>
|
|||
|
|
internal sealed class SqlSelectStatement : ISqlFragment
|
|||
|
|
{
|
|||
|
|
private bool isDistinct;
|
|||
|
|
|
|||
|
|
/// <summary>
|
|||
|
|
/// Do we need to add a DISTINCT at the beginning of the SELECT
|
|||
|
|
/// </summary>
|
|||
|
|
internal bool IsDistinct
|
|||
|
|
{
|
|||
|
|
get { return isDistinct; }
|
|||
|
|
set { isDistinct = value; }
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private List<Symbol> allJoinExtents;
|
|||
|
|
internal List<Symbol> AllJoinExtents
|
|||
|
|
{
|
|||
|
|
get { return allJoinExtents; }
|
|||
|
|
// We have a setter as well, even though this is a list,
|
|||
|
|
// since we use this field only in special cases.
|
|||
|
|
set { allJoinExtents = value; }
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private List<Symbol> fromExtents;
|
|||
|
|
internal List<Symbol> FromExtents
|
|||
|
|
{
|
|||
|
|
get
|
|||
|
|
{
|
|||
|
|
if (null == fromExtents)
|
|||
|
|
{
|
|||
|
|
fromExtents = new List<Symbol>();
|
|||
|
|
}
|
|||
|
|
return fromExtents;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private Dictionary<Symbol, bool> outerExtents;
|
|||
|
|
internal Dictionary<Symbol, bool> OuterExtents
|
|||
|
|
{
|
|||
|
|
get
|
|||
|
|
{
|
|||
|
|
if (null == outerExtents)
|
|||
|
|
{
|
|||
|
|
outerExtents = new Dictionary<Symbol, bool>();
|
|||
|
|
}
|
|||
|
|
return outerExtents;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private TopClause top;
|
|||
|
|
internal TopClause Top
|
|||
|
|
{
|
|||
|
|
get { return top; }
|
|||
|
|
set
|
|||
|
|
{
|
|||
|
|
Debug.Assert(top == null, "SqlSelectStatement.Top has already been set");
|
|||
|
|
top = value;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private SqlBuilder select = new SqlBuilder();
|
|||
|
|
internal SqlBuilder Select
|
|||
|
|
{
|
|||
|
|
get { return select; }
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private SqlBuilder from = new SqlBuilder();
|
|||
|
|
internal SqlBuilder From
|
|||
|
|
{
|
|||
|
|
get { return from; }
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
private SqlBuilder where;
|
|||
|
|
internal SqlBuilder Where
|
|||
|
|
{
|
|||
|
|
get
|
|||
|
|
{
|
|||
|
|
if (null == where)
|
|||
|
|
{
|
|||
|
|
where = new SqlBuilder();
|
|||
|
|
}
|
|||
|
|
return where;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private SqlBuilder groupBy;
|
|||
|
|
internal SqlBuilder GroupBy
|
|||
|
|
{
|
|||
|
|
get
|
|||
|
|
{
|
|||
|
|
if (null == groupBy)
|
|||
|
|
{
|
|||
|
|
groupBy = new SqlBuilder();
|
|||
|
|
}
|
|||
|
|
return groupBy;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private SqlBuilder orderBy;
|
|||
|
|
public SqlBuilder OrderBy
|
|||
|
|
{
|
|||
|
|
get
|
|||
|
|
{
|
|||
|
|
if (null == orderBy)
|
|||
|
|
{
|
|||
|
|
orderBy = new SqlBuilder();
|
|||
|
|
}
|
|||
|
|
return orderBy;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
//indicates whether it is the top most select statement,
|
|||
|
|
// if not Order By should be omitted unless there is a corresponding TOP
|
|||
|
|
private bool isTopMost;
|
|||
|
|
internal bool IsTopMost
|
|||
|
|
{
|
|||
|
|
get { return this.isTopMost; }
|
|||
|
|
set { this.isTopMost = value; }
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
#region ISqlFragment Members
|
|||
|
|
|
|||
|
|
/// <summary>
|
|||
|
|
/// Write out a SQL select statement as a string.
|
|||
|
|
/// We have to
|
|||
|
|
/// <list type="number">
|
|||
|
|
/// <item>Check whether the aliases extents we use in this statement have
|
|||
|
|
/// to be renamed.
|
|||
|
|
/// We first create a list of all the aliases used by the outer extents.
|
|||
|
|
/// For each of the FromExtents( or AllJoinExtents if it is non-null),
|
|||
|
|
/// rename it if it collides with the previous list.
|
|||
|
|
/// </item>
|
|||
|
|
/// <item>Write each of the clauses (if it exists) as a string</item>
|
|||
|
|
/// </list>
|
|||
|
|
/// </summary>
|
|||
|
|
/// <param name="writer"></param>
|
|||
|
|
/// <param name="sqlGenerator"></param>
|
|||
|
|
public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator)
|
|||
|
|
{
|
|||
|
|
#region Check if FROM aliases need to be renamed
|
|||
|
|
|
|||
|
|
// Create a list of the aliases used by the outer extents
|
|||
|
|
// JoinSymbols have to be treated specially.
|
|||
|
|
List<string> outerExtentAliases = null;
|
|||
|
|
if ((null != outerExtents) && (0 < outerExtents.Count))
|
|||
|
|
{
|
|||
|
|
foreach (Symbol outerExtent in outerExtents.Keys)
|
|||
|
|
{
|
|||
|
|
JoinSymbol joinSymbol = outerExtent as JoinSymbol;
|
|||
|
|
if (joinSymbol != null)
|
|||
|
|
{
|
|||
|
|
foreach (Symbol symbol in joinSymbol.FlattenedExtentList)
|
|||
|
|
{
|
|||
|
|
if (null == outerExtentAliases) { outerExtentAliases = new List<string>(); }
|
|||
|
|
outerExtentAliases.Add(symbol.NewName);
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
else
|
|||
|
|
{
|
|||
|
|
if (null == outerExtentAliases) { outerExtentAliases = new List<string>(); }
|
|||
|
|
outerExtentAliases.Add(outerExtent.NewName);
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// An then rename each of the FromExtents we have
|
|||
|
|
// If AllJoinExtents is non-null - it has precedence.
|
|||
|
|
// The new name is derived from the old name - we append an increasing int.
|
|||
|
|
List<Symbol> extentList = this.AllJoinExtents ?? this.fromExtents;
|
|||
|
|
if (null != extentList)
|
|||
|
|
{
|
|||
|
|
foreach (Symbol fromAlias in extentList)
|
|||
|
|
{
|
|||
|
|
if ((null != outerExtentAliases) && outerExtentAliases.Contains(fromAlias.Name))
|
|||
|
|
{
|
|||
|
|
int i = sqlGenerator.AllExtentNames[fromAlias.Name];
|
|||
|
|
string newName;
|
|||
|
|
do
|
|||
|
|
{
|
|||
|
|
++i;
|
|||
|
|
newName = fromAlias.Name + i.ToString(System.Globalization.CultureInfo.InvariantCulture);
|
|||
|
|
}
|
|||
|
|
while (sqlGenerator.AllExtentNames.ContainsKey(newName));
|
|||
|
|
sqlGenerator.AllExtentNames[fromAlias.Name] = i;
|
|||
|
|
fromAlias.NewName = newName;
|
|||
|
|
|
|||
|
|
// Add extent to list of known names (although i is always incrementing, "prefix11" can
|
|||
|
|
// eventually collide with "prefix1" when it is extended)
|
|||
|
|
sqlGenerator.AllExtentNames[newName] = 0;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// Add the current alias to the list, so that the extents
|
|||
|
|
// that follow do not collide with me.
|
|||
|
|
if (null == outerExtentAliases) { outerExtentAliases = new List<string>(); }
|
|||
|
|
outerExtentAliases.Add(fromAlias.NewName);
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
#endregion
|
|||
|
|
|
|||
|
|
// Increase the indent, so that the Sql statement is nested by one tab.
|
|||
|
|
writer.Indent += 1; // ++ can be confusing in this context
|
|||
|
|
|
|||
|
|
writer.Write("SELECT ");
|
|||
|
|
if (IsDistinct)
|
|||
|
|
{
|
|||
|
|
writer.Write("DISTINCT ");
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if (this.Top != null)
|
|||
|
|
{
|
|||
|
|
this.Top.WriteSql(writer, sqlGenerator);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if ((null == this.select) || this.Select.IsEmpty)
|
|||
|
|
{
|
|||
|
|
Debug.Assert(false); // we have removed all possibilities of SELECT *.
|
|||
|
|
writer.Write("*");
|
|||
|
|
}
|
|||
|
|
else
|
|||
|
|
{
|
|||
|
|
this.Select.WriteSql(writer, sqlGenerator);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
writer.WriteLine();
|
|||
|
|
writer.Write("FROM ");
|
|||
|
|
this.From.WriteSql(writer, sqlGenerator);
|
|||
|
|
|
|||
|
|
if ((null != this.where) && !this.Where.IsEmpty)
|
|||
|
|
{
|
|||
|
|
writer.WriteLine();
|
|||
|
|
writer.Write("WHERE ");
|
|||
|
|
this.Where.WriteSql(writer, sqlGenerator);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if ((null != this.groupBy) && !this.GroupBy.IsEmpty)
|
|||
|
|
{
|
|||
|
|
writer.WriteLine();
|
|||
|
|
writer.Write("GROUP BY ");
|
|||
|
|
this.GroupBy.WriteSql(writer, sqlGenerator);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
if ((null != this.orderBy) && !this.OrderBy.IsEmpty && (this.IsTopMost || this.Top != null))
|
|||
|
|
{
|
|||
|
|
writer.WriteLine();
|
|||
|
|
writer.Write("ORDER BY ");
|
|||
|
|
this.OrderBy.WriteSql(writer, sqlGenerator);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
--writer.Indent;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
#endregion
|
|||
|
|
}
|
|||
|
|
}
|