From be84f6dbd62ce9c344e41156463b11d13a307bb4 Mon Sep 17 00:00:00 2001
From: 28810 <28810@YEXIANGQIN>
Date: Thu, 21 Feb 2019 14:30:51 +0800
Subject: [PATCH] add sqlserver2012+ offset fetch next

---
 FreeSql/SqlServer/Curd/SqlServerSelect.cs | 79 ++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 1 deletion(-)

diff --git a/FreeSql/SqlServer/Curd/SqlServerSelect.cs b/FreeSql/SqlServer/Curd/SqlServerSelect.cs
index 658ae0ea..31dd47c8 100644
--- a/FreeSql/SqlServer/Curd/SqlServerSelect.cs
+++ b/FreeSql/SqlServer/Curd/SqlServerSelect.cs
@@ -10,7 +10,11 @@ namespace FreeSql.SqlServer.Curd {
 
 	class SqlServerSelect<T1> : FreeSql.Internal.CommonProvider.Select1Provider<T1> where T1 : class {
 
-		internal static string ToSqlStatic(CommonUtils _commonUtils, string _select, string field, StringBuilder _join, StringBuilder _where, string _groupby, string _having, string _orderby, int _skip, int _limit, List<SelectTableInfo> _tables, IFreeSql _orm) {
+		internal static string ToSqlStatic(CommonUtils _commonUtils, string _select, string field, StringBuilder _join, StringBuilder _where, string _groupby, string _having, string _orderby, int _skip, int _limit, List<SelectTableInfo> _tables, IFreeSql _orm)
+			=> ToSqlStaticRowNumber(_commonUtils, _select, field, _join, _where, _groupby, _having, _orderby, _skip, _limit, _tables, _orm);
+
+		#region SqlServer 2005 row_number
+		internal static string ToSqlStaticRowNumber(CommonUtils _commonUtils, string _select, string field, StringBuilder _join, StringBuilder _where, string _groupby, string _having, string _orderby, int _skip, int _limit, List<SelectTableInfo> _tables, IFreeSql _orm) {
 			if (_orm.CodeFirst.IsAutoSyncStructure)
 				_orm.CodeFirst.SyncStructure(_tables.Select(a => a.Table.Type).ToArray());
 
@@ -80,6 +84,79 @@ namespace FreeSql.SqlServer.Curd {
 
 			return sb.ToString();
 		}
+		#endregion
+
+		#region SqlServer 2012+ offset feach next
+		internal static string ToSqlStaticOffsetFetchNext(CommonUtils _commonUtils, string _select, string field, StringBuilder _join, StringBuilder _where, string _groupby, string _having, string _orderby, int _skip, int _limit, List<SelectTableInfo> _tables, IFreeSql _orm) {
+			if (_orm.CodeFirst.IsAutoSyncStructure)
+				_orm.CodeFirst.SyncStructure(_tables.Select(a => a.Table.Type).ToArray());
+
+			var sb = new StringBuilder();
+			sb.Append(_select);
+			if (_skip <= 0 && _limit > 0) sb.Append("TOP ").Append(_limit).Append(" ");
+			sb.Append(field);
+			sb.Append(" \r\nFROM ");
+			var tbsjoin = _tables.Where(a => a.Type != SelectTableInfoType.From).ToArray();
+			var tbsfrom = _tables.Where(a => a.Type == SelectTableInfoType.From).ToArray();
+			for (var a = 0; a < tbsfrom.Length; a++) {
+				sb.Append(_commonUtils.QuoteSqlName(tbsfrom[a].Table.DbName)).Append(" ").Append(tbsfrom[a].Alias);
+				if (tbsjoin.Length > 0) {
+					//如果存在 join 查询，则处理 from t1, t2 改为 from t1 inner join t2 on 1 = 1
+					for (var b = 1; b < tbsfrom.Length; b++)
+						sb.Append(" \r\nLEFT JOIN ").Append(_commonUtils.QuoteSqlName(tbsfrom[b].Table.DbName)).Append(" ").Append(tbsfrom[b].Alias).Append(" ON 1 = 1");
+					break;
+				}
+				if (a < tbsfrom.Length - 1) sb.Append(", ");
+			}
+			foreach (var tb in tbsjoin) {
+				if (tb.Type == SelectTableInfoType.Parent) continue;
+				switch (tb.Type) {
+					case SelectTableInfoType.LeftJoin:
+						sb.Append(" \r\nLEFT JOIN ");
+						break;
+					case SelectTableInfoType.InnerJoin:
+						sb.Append(" \r\nINNER JOIN ");
+						break;
+					case SelectTableInfoType.RightJoin:
+						sb.Append(" \r\nRIGHT JOIN ");
+						break;
+				}
+				sb.Append(_commonUtils.QuoteSqlName(tb.Table.DbName)).Append(" ").Append(tb.Alias).Append(" ON ").Append(tb.On);
+			}
+			if (_join.Length > 0) sb.Append(_join);
+
+			var sbqf = new StringBuilder();
+			foreach (var tb in _tables) {
+				if (tb.Type == SelectTableInfoType.Parent) continue;
+				if (string.IsNullOrEmpty(tb.Table.SelectFilter) == false)
+					sbqf.Append(" AND (").Append(tb.Table.SelectFilter.Replace("a.", $"{tb.Alias}.")).Append(")");
+			}
+			if (_where.Length > 0) {
+				sb.Append(" \r\nWHERE ").Append(_where.ToString().Substring(5));
+				if (sbqf.Length > 0) sb.Append(sbqf.ToString());
+			} else {
+				if (sbqf.Length > 0) sb.Append(" \r\nWHERE ").Append(sbqf.Remove(0, 5));
+			}
+			if (string.IsNullOrEmpty(_groupby) == false) {
+				sb.Append(_groupby);
+				if (string.IsNullOrEmpty(_having) == false)
+					sb.Append(" \r\nHAVING ").Append(_having.Substring(5));
+			}
+			if (_skip > 0) {
+				if (string.IsNullOrEmpty(_orderby)) {
+					var pktb = _tables.Where(a => a.Table.Primarys.Any()).FirstOrDefault();
+					if (pktb != null) _orderby = string.Concat(" \r\nORDER BY ", pktb.Alias, ".", _commonUtils.QuoteSqlName(pktb?.Table.Primarys.First().Attribute.Name));
+					else _orderby = string.Concat(" \r\nORDER BY ", _tables.First().Alias, ".", _commonUtils.QuoteSqlName(_tables.First().Table.Columns.First().Value.Attribute.Name));
+				}
+				sb.Append(_orderby).Append($" \r\nOFFSET {_skip} ROW");
+				if (_limit > 0) sb.Append($" \r\nFETCH NEXT {_limit} ROW ONLY");
+			} else {
+				sb.Append(_orderby);
+			}
+
+			return sb.ToString();
+		}
+		#endregion
 
 		public SqlServerSelect(IFreeSql orm, CommonUtils commonUtils, CommonExpression commonExpression, object dywhere) : base(orm, commonUtils, commonExpression, dywhere) { }
 		public override ISelect<T1, T2, T3> From<T2, T3>(Expression<Func<ISelectFromExpression<T1>, T2, T3, ISelectFromExpression<T1>>> exp) { this.InternalFrom(exp?.Body); var ret = new SqlServerSelect<T1, T2, T3>(_orm, _commonUtils, _commonExpression, null); SqlServerSelect<T1>.CopyData(this, ret); return ret; }