public override IQueryState Accept(TakeExpression exp)
{
GeneralQueryState subQueryState = this.AsSubQueryState();
TakeQueryState state = new TakeQueryState(subQueryState.Result, exp.Count);
return(state);
}
public virtual GeneralQueryState AsSubQueryState()
{
DbSqlQueryExpression sqlQuery = this.CreateSqlQuery();
DbSubQueryExpression subQuery = new DbSubQueryExpression(sqlQuery);
ResultElement result = new ResultElement(this._resultElement.ScopeParameters, this._resultElement.ScopeTables);
DbTableSegment tableSeg = new DbTableSegment(subQuery, result.GenerateUniqueTableAlias());
DbFromTableExpression fromTable = new DbFromTableExpression(tableSeg);
result.FromTable = fromTable;
DbTable table = new DbTable(tableSeg.Alias);
//TODO 根据旧的生成新 MappingMembers
IMappingObjectExpression newMoe = this.Result.MappingObjectExpression.ToNewObjectExpression(sqlQuery, table);
result.MappingObjectExpression = newMoe;
//得将 subQuery.SqlQuery.Orders 告诉 以下创建的 result
//将 orderPart 传递下去
if (this.Result.Orderings.Count > 0)
{
for (int i = 0; i < this.Result.Orderings.Count; i++)
{
DbOrdering ordering = this.Result.Orderings[i];
DbExpression orderingExp = ordering.Expression;
string alias = null;
DbColumnSegment columnExpression = sqlQuery.ColumnSegments.Find(a => DbExpressionEqualityComparer.EqualsCompare(orderingExp, a.Body));
// 对于重复的则不需要往 sqlQuery.Columns 重复添加了
if (columnExpression != null)
{
alias = columnExpression.Alias;
}
else
{
alias = Utils.GenerateUniqueColumnAlias(sqlQuery);
DbColumnSegment columnSeg = new DbColumnSegment(orderingExp, alias);
sqlQuery.ColumnSegments.Add(columnSeg);
}
DbColumnAccessExpression columnAccessExpression = new DbColumnAccessExpression(table, DbColumn.MakeColumn(orderingExp, alias));
result.Orderings.Add(new DbOrdering(columnAccessExpression, ordering.OrderType));
}
}
result.InheritOrderings = true;
GeneralQueryState queryState = new GeneralQueryState(result);
return(queryState);
}
