protected override Expression VisitSelect(SqlSelectExpression select)
{
var columnRemoved = false;
select = (SqlSelectExpression)base.VisitSelect(select);
var columnsOrderedByName = select.Columns.OrderBy(c => c.Name).ToList();
var removedColumns = new BitArray(select.Columns.Count);
for (int i = 0, n = columnsOrderedByName.Count; i < n - 1; i++)
{
var icolumn = columnsOrderedByName[i];
var iNewColumnExpression = new SqlColumnExpression(icolumn.Expression.Type, select.Alias, icolumn.Name);
for (var j = i + 1; j < n; j++)
{
if (!removedColumns.Get(j))
{
var jcolumn = columnsOrderedByName[j];
if (IsSameExpression(icolumn.Expression, jcolumn.Expression))
{
// 'j' references should now be a reference to 'i'
var jNewColumnExpression = new SqlColumnExpression(jcolumn.Expression.Type, select.Alias, jcolumn.Name);
this.visitedColumns.Add(jNewColumnExpression, iNewColumnExpression);
removedColumns.Set(j, true);
columnRemoved = true;
}
}
}
}
if (columnRemoved)
{
var newColumnDeclarations = new List <SqlColumnDeclaration>();
for (int i = 0, n = columnsOrderedByName.Count; i < n; i++)
{
if (!removedColumns.Get(i))
{
newColumnDeclarations.Add(columnsOrderedByName[i]);
}
}
select = select.ChangeColumns(newColumnDeclarations);
}
return(select);
}
protected override Expression VisitSelect(SqlSelectExpression selectExpression)
{
if (selectExpression.Skip != null)
{
const string orderByColumnPrefix = "__$$ORDERBYCOL";
var rowNumber = new SqlFunctionCallExpression(typeof(int), "ROW_NUMBER");
var selectWithRowAlias = selectExpression.Alias + "_ROW";
var cols = selectExpression
.Columns
.Select(c => new SqlColumnDeclaration(c.Name, new SqlColumnExpression(c.Expression.Type, selectExpression.Alias, c.Name)))
.ToList();
var aliasedNames = selectExpression.OrderBy == null ? null : new HashSet <string>(selectExpression
.Columns
.Select(c => c.Expression)
.OfType <SqlColumnExpression>()
.Select(c => c.AliasedName));
var orderByCols = selectExpression
.OrderBy?
.Where(c => !IsColumnAndAlreadyProjected(c.Expression, aliasedNames))
.Select((c, i) => new SqlColumnDeclaration(orderByColumnPrefix + i, c.Expression)) ?? Enumerable.Empty <SqlColumnDeclaration>();
SqlOverExpression over;
if (selectExpression.OrderBy?.Any() == true)
{
var i = 0;
over = new SqlOverExpression(rowNumber, selectExpression
.OrderBy
.Select(c =>
{
if (IsColumnAndAlreadyProjected(c.Expression, aliasedNames))
{
return(new SqlOrderByExpression(c.OrderType, new SqlColumnExpression(c.Type, selectExpression.Alias, ((SqlColumnExpression)c.Expression).Name)));
}
else
{
return(new SqlOrderByExpression(c.OrderType, new SqlColumnExpression(c.Type, selectExpression.Alias, orderByColumnPrefix + i++)));
}
}).ToReadOnlyCollection());
}
else
{
over = new SqlOverExpression(rowNumber, cols.Select(c => new SqlOrderByExpression(OrderType.Ascending, c.Expression)).ToReadOnlyCollection());
}
var innerSelect = orderByCols == null ? selectExpression : selectExpression.ChangeColumns(selectExpression.Columns.Concat(orderByCols));
var rowColumn = new SqlColumnDeclaration(RowColumnName, over);
cols.Add(rowColumn);
var selectWithRowColumns = cols.ToReadOnlyCollection();
var selectWithRow = new SqlSelectExpression(selectExpression.Type, selectWithRowAlias, selectWithRowColumns, Visit(innerSelect.ChangeOrderBy(null).ChangeSkipTake(null, null)), null, null, null, false, null, null, false);
var outerColumns = selectExpression.Columns.Select(c => new SqlColumnDeclaration(c.Name, new SqlColumnExpression(c.Expression.Type, selectWithRowAlias, c.Name)));
Expression rowPredicate = Expression.GreaterThan(new SqlColumnExpression(typeof(int), selectWithRowAlias, rowColumn.Name), selectExpression.Skip);
if (selectExpression.Take != null && !(selectExpression.Take is SqlTakeAllValueExpression))
{
rowPredicate = Expression.And
(
rowPredicate,
Expression.LessThanOrEqual(new SqlColumnExpression(typeof(int), selectWithRowAlias, rowColumn.Name), Expression.Add(selectExpression.Skip, selectExpression.Take))
);
}
var retval = new SqlSelectExpression(selectExpression.Type, selectExpression.Alias, outerColumns.ToReadOnlyCollection(), selectWithRow, rowPredicate, null, null, selectExpression.Distinct, null, null, selectExpression.ForUpdate, selectExpression.Reverse, selectExpression.Into);
return(retval);
}
return(base.VisitSelect(selectExpression));
}
protected override Expression VisitSelect(SqlSelectExpression selectExpression)
{
List <SqlColumnDeclaration> newColumns = null;
for (var i = 0; i < selectExpression.Columns.Count; i++)
{
var column = selectExpression.Columns[i];
var visitedColumnExpression = this.Visit(column.Expression);
if (visitedColumnExpression.Type.GetUnwrappedNullableType() == typeof(bool) && !(visitedColumnExpression is BitBooleanExpression))
{
if (newColumns == null)
{
newColumns = new List <SqlColumnDeclaration>(selectExpression.Columns.Take(i));
}
var newColumnExpression = BitBooleanExpression.Coerce(visitedColumnExpression);
var newColumnDeclaration = new SqlColumnDeclaration(column.Name, newColumnExpression);
newColumns.Add(newColumnDeclaration);
}
else if (visitedColumnExpression != column.Expression)
{
if (newColumns == null)
{
newColumns = new List <SqlColumnDeclaration>(selectExpression.Columns.Take(i));
}
newColumns.Add(column.ReplaceExpression(visitedColumnExpression));
}
else if (newColumns != null)
{
newColumns.Add(column);
}
}
var where = this.Visit(selectExpression.Where);
if ((where is BitBooleanExpression))
{
where = Expression.Equal(where, Expression.Constant(true));
}
if (where != selectExpression.Where)
{
if (newColumns != null)
{
return(selectExpression.ChangeWhereAndColumns(where, new ReadOnlyList <SqlColumnDeclaration>(newColumns)));
}
else
{
return(selectExpression.ChangeWhere(where));
}
}
else if (newColumns != null)
{
return(selectExpression.ChangeColumns(newColumns, true));
}
else
{
return(base.VisitSelect(selectExpression));
}
}