public override void Visit(DbConstantExpression expression)
{
if (generateParameters)
{
var parameter = CreateParameter(expression.Value, expression.ResultType);
_commandText.Append(parameter.ParameterName);
}
else
{
using (var writer = new SqlWriter(_commandText))
{
var sqlGenerator = new SqlGenerator();
sqlGenerator.WriteSql(writer, expression.Accept(sqlGenerator));
}
}
}
/// <summary>
/// Write this symbol out as a string for sql. This is just
/// the new name of the symbol (which could be the same as the old name).
///
/// We rename columns here if necessary.
/// </summary>
/// <param name="writer"></param>
/// <param name="sqlGenerator"></param>
public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator)
{
if (NeedsRenaming)
{
string newName;
var i = sqlGenerator.AllColumnNames[NewName];
do
{
++i;
newName = Name + i.ToString(System.Globalization.CultureInfo.InvariantCulture);
} while (sqlGenerator.AllColumnNames.ContainsKey(newName));
sqlGenerator.AllColumnNames[NewName] = i;
// Prevent it from being renamed repeatedly.
NeedsRenaming = false;
NewName = newName;
// Add this column name to list of known names so that there are no subsequent
// collisions
sqlGenerator.AllColumnNames[newName] = 0;
}
writer.Write(SqlGenerator.QuoteIdentifier(NewName));
}
public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator)
{
// Symbol pair should never be part of a SqlBuilder.
Debug.Assert(false);
}
/// <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 = AllJoinExtents ?? _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 (First != null)
{
First.WriteSql(writer, sqlGenerator);
}
if (Skip != null)
{
Skip.WriteSql(writer, sqlGenerator);
}
if ((_select == null) || Select.IsEmpty)
{
Debug.Assert(false); // we have removed all possibilities of SELECT *.
writer.Write("*");
}
else
{
Select.WriteSql(writer, sqlGenerator);
}
writer.WriteLine();
writer.Write("FROM ");
From.WriteSql(writer, sqlGenerator);
if ((_where != null) && !Where.IsEmpty)
{
writer.WriteLine();
writer.Write("WHERE ");
Where.WriteSql(writer, sqlGenerator);
}
if ((_groupBy != null) && !GroupBy.IsEmpty)
{
writer.WriteLine();
writer.Write("GROUP BY ");
GroupBy.WriteSql(writer, sqlGenerator);
}
if ((_orderBy != null) && !OrderBy.IsEmpty && (IsTopMost || First != null || Skip != null))
{
writer.WriteLine();
writer.Write("ORDER BY ");
OrderBy.WriteSql(writer, sqlGenerator);
}
--writer.Indent;
}
