public static DbSelectExpression AddColumn(this DbSelectExpression select, DbColumnDeclaration column)
{
var columns = new List <DbColumnDeclaration>(select.Columns)
{
column
};
return(select.SetColumns(columns));
}
public static DbSelectExpression RemoveColumn(this DbSelectExpression select, DbColumnDeclaration column)
{
var columns = new List <DbColumnDeclaration>(select.Columns);
if (columns != null)
{
columns.Remove(column);
}
return(select.SetColumns(columns));
}
protected override Expression VisitSelect(DbSelectExpression select)
{
select = base.VisitSelect(select) as DbSelectExpression;
var cols = select.Columns.OrderBy(c => c.Name).ToList();
var removed = new BitArray(select.Columns.Count);
var anyRemoved = false;
for (int i = 0, n = cols.Count; i < n - 1; i++)
{
var ci = cols[i];
var cix = ci.Expression as DbColumnExpression;
var qt = cix != null ? cix.QueryType : ci.QueryType;
var cxi = new DbColumnExpression(ci.Expression.Type, qt, select.Alias, ci.Name);
for (int j = i + 1; j < n; j++)
{
if (!removed.Get(j))
{
var cj = cols[j];
if (SameExpression(ci.Expression, cj.Expression))
{
var cxj = new DbColumnExpression(cj.Expression.Type, qt, select.Alias, cj.Name);
this.map.Add(cxj, cxi);
removed.Set(j, true);
anyRemoved = true;
}
}
}
}
if (anyRemoved)
{
var newDecls = new List <DbColumnDeclaration>();
for (int i = 0, n = cols.Count; i < n; i++)
{
if (!removed.Get(i))
{
newDecls.Add(cols[i]);
}
}
select = select.SetColumns(newDecls);
}
return(select);
}