protected override Expression VisitJoin(SqlJoinExpression join)
{
join = (SqlJoinExpression)base.VisitJoin(join);
if (join.JoinType == SqlJoinType.Cross && this.currentWhere != null)
{
var declaredLeft = SqlDeclaredAliasGatherer.Gather(join.Left);
var declaredRight = SqlDeclaredAliasGatherer.Gather(join.Right);
var declared = new HashSet <string>(declaredLeft.Union(declaredRight));
var exprs = this.currentWhere.Split(ExpressionType.And, ExpressionType.AndAlso);
var good = exprs.Where(e => CanBeJoinCondition(e, declaredLeft, declaredRight, declared)).ToList();
if (good.Count > 0)
{
var condition = good.Join(ExpressionType.And);
join = this.UpdateJoin(join, SqlJoinType.Inner, join.Left, join.Right, condition);
var newWhere = exprs.Where(e => !good.Contains(e)).Join(ExpressionType.And);
this.currentWhere = newWhere;
}
}
return(join);
}
public static HashSet <string> Gather(Expression source)
{
var gatherer = new SqlDeclaredAliasGatherer();
gatherer.Visit(source);
return(gatherer.aliases);
}
public static HashSet<string> Gather(Expression source)
{
var gatherer = new SqlDeclaredAliasGatherer();
gatherer.Visit(source);
return gatherer.aliases;
}
protected override Expression VisitJoin(SqlJoinExpression join)
{
join = (SqlJoinExpression)base.VisitJoin(join);
if (join.JoinType == SqlJoinType.CrossApply || join.JoinType == SqlJoinType.OuterApply)
{
if (join.Right is SqlTableExpression)
{
return(new SqlJoinExpression(join.Type, SqlJoinType.Cross, join.Left, join.Right, null));
}
else
{
var select = join.Right as SqlSelectExpression;
if (select != null && select.Take == null && select.Skip == null && !SqlAggregateChecker.HasAggregates(select) && (select.GroupBy == null || select.GroupBy.Count == 0))
{
var selectWithoutWhere = select.ChangeWhere(null);
var referencedAliases = SqlReferencedAliasGatherer.Gather(selectWithoutWhere);
var declaredAliases = SqlDeclaredAliasGatherer.Gather(join.Left);
referencedAliases.IntersectWith(declaredAliases);
if (referencedAliases.Count == 0)
{
var where = select.Where;
select = selectWithoutWhere;
var pc = ColumnProjector.ProjectColumns(new Nominator(Nominator.CanBeColumn), where, select.Columns, select.Alias, SqlDeclaredAliasGatherer.Gather(select.From));
select = select.ChangeColumns(pc.Columns);
where = pc.Projector;
var joinType = (where == null) ? SqlJoinType.Cross : (join.JoinType == SqlJoinType.CrossApply ? SqlJoinType.Inner : SqlJoinType.Left);
return(new SqlJoinExpression(typeof(void), joinType, join.Left, select, where));
}
}
}
}
return(join);
}
