/// <summary>
/// Visits the select.
/// </summary>
/// <param name="select">The select.</param>
/// <returns></returns>
protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null && select.Take != null && select.OrderBy.Count > 0)
{
var skip = select.Skip;
var take = select.Take;
var skipPlusTake = PartialEvaluator.Eval(Expression.Add(skip, take));
select = select.SetTake(skipPlusTake).SetSkip(null);
select = select.AddRedundantSelect(this.language, new TableAlias());
select = select.SetTake(take);
// propagate order-bys to new layer
select = (SelectExpression)OrderByRewriter.Rewrite(this.language, select);
var inverted = select.OrderBy.Select(ob => new OrderExpression(ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending, ob.Expression));
select = select.SetOrderBy(inverted);
select = select.AddRedundantSelect(this.language, new TableAlias());
select = select.SetTake(Expression.Constant(0)); // temporary
select = (SelectExpression)OrderByRewriter.Rewrite(this.language, select);
var reverted = select.OrderBy.Select(ob => new OrderExpression(ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending, ob.Expression));
select = select.SetOrderBy(reverted);
select = select.SetTake(null);
}
return(select);
}
/// <summary>
///
/// </summary>
/// <param name="select"></param>
/// <returns></returns>
protected override Expression VisitSelect(SelectExpression select)
{
switch (_dataType)
{
case Nequeo.Data.DataType.ConnectionContext.ConnectionDataType.OracleDataType:
case Nequeo.Data.DataType.ConnectionContext.ConnectionDataType.SqlDataType:
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(null).SetTake(null);
bool canAddColumn = !select.IsDistinct && (select.GroupBy == null || select.GroupBy.Count == 0);
if (!canAddColumn)
{
newSelect = newSelect.AddRedundantSelect(new TableAlias());
}
newSelect = newSelect.AddColumn(new ColumnDeclaration("ROW_NUM", new RowNumberExpression(select.OrderBy)));
// add layer for WHERE clause that references new rownum column
newSelect = newSelect.AddRedundantSelect(new TableAlias());
newSelect = newSelect.RemoveColumn(newSelect.Columns[newSelect.Columns.Count - 1]);
var newAlias = ((SelectExpression)newSelect.From).Alias;
ColumnExpression rnCol = new ColumnExpression(typeof(int), newAlias, "ROW_NUM");
Expression where;
if (select.Take != null)
{
where = new BetweenExpression(rnCol, Expression.Add(select.Skip, Expression.Constant(1)), Expression.Add(select.Skip, select.Take));
}
else
{
where = Expression.GreaterThan(rnCol, select.Skip);
}
if (newSelect.Where != null)
{
where = Expression.And(newSelect.Where, where);
}
newSelect = newSelect.SetWhere(where);
select = newSelect;
}
return(select);
default:
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(select.Skip).SetTake(select.Take);
select = newSelect;
}
return(select);
}
}
protected override Expression VisitSelect(SelectExpression select)
{
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null)
{
SelectExpression newSelect = select.SetSkip(null).SetTake(null);
bool canAddColumn = !select.IsDistinct && (select.GroupBy == null || select.GroupBy.Count == 0);
if (!canAddColumn)
{
newSelect = newSelect.AddRedundantSelect(new TableAlias());
}
newSelect = newSelect.AddColumn(new ColumnDeclaration(COLUMN_NAME, new RowNumberExpression(select.OrderBy)));
// add layer for WHERE clause that references new rownum column
newSelect = newSelect.AddRedundantSelect(new TableAlias());
newSelect = newSelect.RemoveColumn(newSelect.Columns.Single(c => c.Name == COLUMN_NAME));
var newAlias = ((SelectExpression)newSelect.From).Alias;
ColumnExpression rnCol = new ColumnExpression(typeof(int), newAlias, COLUMN_NAME, null);
Expression where;
if (select.Take != null)
{
where = new BetweenExpression(rnCol, Expression.Add(select.Skip, Expression.Constant(1)), Expression.Add(select.Skip, select.Take));
}
else
{
where = rnCol.GreaterThan(select.Skip);
}
if (newSelect.Where != null)
{
where = newSelect.Where.And(where);
}
newSelect = newSelect.SetWhere(where);
select = newSelect;
}
return(select);
}
protected override Expression VisitSelect(SelectExpression select)
{
// select * from table order by x skip s take t
// =>
// select * from (select top s * from (select top s + t from table order by x) order by -x) order by x
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null && select.Take != null && select.OrderBy.Count > 0)
{
var skip = select.Skip;
var take = select.Take;
var skipPlusTake = PartialEvaluator.Eval(Expression.Add(skip, take));
select = select.SetTake(skipPlusTake).SetSkip(null);
select = select.AddRedundantSelect(new TableAlias());
select = select.SetTake(take);
// propogate order-bys to new layer
select = (SelectExpression) new OrderByRewriter().Visit(select);
var inverted = select.OrderBy.Select(ob => new OrderExpression(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
ob.Expression
));
select = select.SetOrderBy(inverted);
select = select.AddRedundantSelect(new TableAlias());
select = select.SetTake(Expression.Constant(0)); // temporary
select = (SelectExpression) new OrderByRewriter().Visit(select);
var reverted = select.OrderBy.Select(ob => new OrderExpression(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
ob.Expression
));
select = select.SetOrderBy(reverted);
select = select.SetTake(null);
}
return(select);
}
protected override Expression VisitSelect(SelectExpression select)
{
// select * from table order by x skip s take t
// =>
// select * from (select top s * from (select top s + t from table order by x) order by -x) order by x
select = (SelectExpression)base.VisitSelect(select);
if (select.Skip != null && select.Take != null && select.OrderBy.Count > 0)
{
var skip = select.Skip;
var take = select.Take;
var skipPlusTake = PartialEvaluator.Eval(Expression.Add(skip, take));
select = select.SetTake(skipPlusTake).SetSkip(null);
select = select.AddRedundantSelect(new TableAlias());
select = select.SetTake(take);
// propogate order-bys to new layer
select = (SelectExpression)OrderByRewriter.Rewrite(select);
var inverted =
select.OrderBy.Select(
ob =>
new OrderExpression(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending, ob.Expression));
select = select.SetOrderBy(inverted);
select = select.AddRedundantSelect(new TableAlias());
select = select.SetTake(Expression.Constant(0)); // temporary
select = (SelectExpression)OrderByRewriter.Rewrite(select);
var reverted =
select.OrderBy.Select(
ob =>
new OrderExpression(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending, ob.Expression));
select = select.SetOrderBy(reverted);
select = select.SetTake(null);
}
return select;
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
if (isTopLevel)
{
isTopLevel = false;
currentSelect = proj.Select;
var projector = Visit(proj.Projector);
if (projector != proj.Projector || currentSelect != proj.Select)
{
return(new ProjectionExpression(currentSelect, projector, proj.Aggregator, proj.IsAsync));
}
return(proj);
}
if (proj.IsSingleton && CanJoinOnServer(currentSelect))
{
var newAlias = new TableAlias();
currentSelect = currentSelect.AddRedundantSelect(newAlias);
var source = (SelectExpression)ColumnMapper.Map(proj.Select, newAlias, currentSelect.Alias);
var pex = new ProjectionExpression(source, proj.Projector, proj.IsAsync).AddOuterJoinTest();
var pc = ColumnProjector.ProjectColumns(QueryUtility.CanBeColumnExpression, pex.Projector, currentSelect.Columns, currentSelect.Alias, newAlias, proj.Select.Alias);
// **fix** 解决返回关联对象后使用Distinct的问题
var join = CreateJoinExpression(currentSelect.From, pex.Select, out bool isDistinct);
currentSelect = new SelectExpression(currentSelect.Alias, pc.Columns, join, null);
if (isDistinct)
{
var newPc = ColumnProjector.ProjectColumns(QueryUtility.CanBeColumnExpression, proj.Projector, null, currentSelect.Alias, proj.Select.Alias);
currentSelect = new SelectExpression(currentSelect.Alias, newPc.Columns, currentSelect, null, null, null, isDistinct, null, null, null, null, false);
return(Visit(newPc.Projector));
}
return(Visit(pc.Projector));
}
var saveTop = isTopLevel;
var saveSelect = currentSelect;
isTopLevel = true;
currentSelect = null;
var result = base.VisitProjection(proj);
isTopLevel = saveTop;
currentSelect = saveSelect;
return(result);
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
if (isTopLevel)
{
isTopLevel = false;
currentSelect = proj.Source;
Expression projector = Visit(proj.Projector);
if (projector != proj.Projector || currentSelect != proj.Source)
{
return(new ProjectionExpression(currentSelect, projector, proj.Aggregator));
}
return(proj);
}
if (proj.IsSingleton && CanJoinOnServer(currentSelect))
{
TableAlias newAlias = new TableAlias();
currentSelect = currentSelect.AddRedundantSelect(newAlias);
// remap any references to the outer select to the new alias;
SelectExpression source =
(SelectExpression)ColumnMapper.Map(proj.Source, newAlias, currentSelect.Alias);
// add outer-join test
ProjectionExpression pex = new ProjectionExpression(source, proj.Projector).AddOuterJoinTest();
var pc = ColumnProjector.ProjectColumns(language.CanBeColumn, pex.Projector, currentSelect.Columns,
currentSelect.Alias, newAlias, proj.Source.Alias);
JoinExpression join = new JoinExpression(JoinType.OuterApply, currentSelect.From, pex.Source, null);
currentSelect = new SelectExpression(currentSelect.Alias, pc.Columns, join, null);
return(Visit(pc.Projector));
}
var saveTop = isTopLevel;
var saveSelect = currentSelect;
isTopLevel = true;
currentSelect = null;
Expression result = base.VisitProjection(proj);
isTopLevel = saveTop;
currentSelect = saveSelect;
return(result);
}