public static SelectExpression Remove(SelectExpression outerSelect, IEnumerable <SelectExpression> selectsToRemove) { return((SelectExpression) new SubqueryRemover(selectsToRemove).Visit(outerSelect)); }
public static HashSet <ColumnExpression> Gather(HashSet <TableAlias> aliases, SelectExpression select) { var gatherer = new JoinColumnGatherer(aliases); gatherer.Gather(select.Where); return(gatherer.columns); }
public static SelectExpression Remove(SelectExpression outerSelect, params SelectExpression[] selectsToRemove) { return(Remove(outerSelect, (IEnumerable <SelectExpression>)selectsToRemove)); }
protected override Expression VisitSelect(SelectExpression select) { // visit column projection first ReadOnlyCollection <ColumnDeclaration> columns = select.Columns; var wasRetained = this.retainAllColumns; this.retainAllColumns = false; List <ColumnDeclaration> alternate = null; for (int i = 0, n = select.Columns.Count; i < n; i++) { ColumnDeclaration decl = select.Columns[i]; if (wasRetained || select.IsDistinct || IsColumnUsed(select.Alias, decl.Name)) { Expression expr = this.Visit(decl.Expression); if (expr != decl.Expression) { decl = new ColumnDeclaration(decl.Name, expr, decl.QueryType); } } else { decl = null; // null means it gets omitted } if (decl != select.Columns[i] && alternate == null) { alternate = new List <ColumnDeclaration>(); for (int j = 0; j < i; j++) { alternate.Add(select.Columns[j]); } } if (decl != null && alternate != null) { alternate.Add(decl); } } if (alternate != null) { columns = alternate.AsReadOnly(); } Expression take = this.Visit(select.Take); Expression skip = this.Visit(select.Skip); ReadOnlyCollection <Expression> groupbys = this.VisitExpressionList(select.GroupBy); ReadOnlyCollection <OrderExpression> orderbys = this.VisitOrderBy(select.OrderBy); Expression where = this.Visit(select.Where); Expression from = this.Visit(select.From); ClearColumnsUsed(select.Alias); if (columns != select.Columns || take != select.Take || skip != select.Skip || orderbys != select.OrderBy || groupbys != select.GroupBy || where != select.Where || from != select.From) { select = new SelectExpression(select.Alias, columns, from, where, orderbys, groupbys, select.IsDistinct, skip, take, select.IsReverse); } this.retainAllColumns = wasRetained; return(select); }
private static bool CanMergeWithFrom(SelectExpression select, bool isTopLevel) { SelectExpression fromSelect = GetLeftMostSelect(select.From); if (fromSelect == null) { return(false); } if (!IsColumnProjection(fromSelect)) { return(false); } bool selHasNameMapProjection = IsNameMapProjection(select); bool selHasOrderBy = select.OrderBy != null && select.OrderBy.Count > 0; bool selHasGroupBy = select.GroupBy != null && select.GroupBy.Count > 0; bool selHasAggregates = AggregateChecker.HasAggregates(select); bool selHasJoin = select.From is JoinExpression; bool frmHasOrderBy = fromSelect.OrderBy != null && fromSelect.OrderBy.Count > 0; bool frmHasGroupBy = fromSelect.GroupBy != null && fromSelect.GroupBy.Count > 0; bool frmHasAggregates = AggregateChecker.HasAggregates(fromSelect); // both cannot have orderby if (selHasOrderBy && frmHasOrderBy) { return(false); } // both cannot have groupby if (selHasGroupBy && frmHasGroupBy) { return(false); } // these are distinct operations if (select.IsReverse || fromSelect.IsReverse) { return(false); } // cannot move forward order-by if outer has group-by if (frmHasOrderBy && (selHasGroupBy || selHasAggregates || select.IsDistinct)) { return(false); } // cannot move forward group-by if outer has where clause if (frmHasGroupBy /*&& (select.Where != null)*/) // need to assert projection is the same in order to move group-by forward { return(false); } // cannot move forward a take if outer has take or skip or distinct if (fromSelect.Take != null && (select.Take != null || select.Skip != null || select.IsDistinct || selHasAggregates || selHasGroupBy || selHasJoin)) { return(false); } // cannot move forward a skip if outer has skip or distinct if (fromSelect.Skip != null && (select.Skip != null || select.IsDistinct || selHasAggregates || selHasGroupBy || selHasJoin)) { return(false); } // cannot move forward a distinct if outer has take, skip, groupby or a different projection if (fromSelect.IsDistinct && (select.Take != null || select.Skip != null || !selHasNameMapProjection || selHasGroupBy || selHasAggregates || (selHasOrderBy && !isTopLevel) || selHasJoin)) { return(false); } if (frmHasAggregates && (select.Take != null || select.Skip != null || select.IsDistinct || selHasAggregates || selHasGroupBy || selHasJoin)) { return(false); } return(true); }
internal static bool IsInitialProjection(SelectExpression select) { return(select.From is TableExpression); }
protected override Expression VisitSelect(SelectExpression select) { this.selects.Add(select); return(select); // don't visit sub-queries }