mcs/class/referencesource/System.Data.Entity/System/Data/SqlClient/SqlGen/TopClause.cs

   1 //---------------------------------------------------------------------
   2 // <copyright file="TopClause.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 //
   6 // @owner  Microsoft
   7 // @backupOwner Microsoft
   8 //---------------------------------------------------------------------
   9
  10 using System;
  11 using System.Collections.Generic;
  12 using System.Diagnostics;
  13 using System.Globalization;
  14 using System.IO;
  15 using System.Text;
  16 using System.Data.SqlClient;
  17 using System.Data.Metadata.Edm;
  18 using System.Data.Common.CommandTrees;
  19
  20 namespace System.Data.SqlClient.SqlGen
  21 {
  22     /// <summary>
  23     /// TopClause represents the a TOP expression in a SqlSelectStatement.
  24     /// It has a count property, which indicates how many TOP rows should be selected and a
  25     /// boolen WithTies property.
  26     /// </summary>
  27     class TopClause : ISqlFragment
  28     {
  29         ISqlFragment topCount;
  30         bool withTies;
  31
  32         /// <summary>
  33         /// Do we need to add a WITH_TIES to the top statement
  34         /// </summary>
  35         internal bool WithTies
  36         {
  37             get { return withTies; }
  38         }
  39
  40         /// <summary>
  41         /// How many top rows should be selected.
  42         /// </summary>
  43         internal ISqlFragment TopCount
  44         {
  45             get { return topCount; }
  46         }
  47
  48         /// <summary>
  49         /// Creates a TopClause with the given topCount and withTies.
  50         /// </summary>
  51         /// <param name="topCount"></param>
  52         /// <param name="withTies"></param>
  53         internal TopClause(ISqlFragment topCount, bool withTies)
  54         {
  55             this.topCount = topCount;
  56             this.withTies = withTies;
  57         }
  58
  59         /// <summary>
  60         /// Creates a TopClause with the given topCount and withTies.
  61         /// </summary>
  62         /// <param name="topCount"></param>
  63         /// <param name="withTies"></param>
  64         internal TopClause(int topCount, bool withTies)
  65         {
  66             SqlBuilder sqlBuilder = new SqlBuilder();
  67             sqlBuilder.Append(topCount.ToString(CultureInfo.InvariantCulture));
  68             this.topCount = sqlBuilder;
  69             this.withTies = withTies;
  70         }
  71
  72         #region ISqlFragment Members
  73
  74         /// <summary>
  75         /// Write out the TOP part of sql select statement
  76         /// It basically writes TOP (X) [WITH TIES].
  77         /// The brackets around X are ommited for Sql8.
  78         /// </summary>
  79         /// <param name="writer"></param>
  80         /// <param name="sqlGenerator"></param>
  81         public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator)
  82         {
  83             writer.Write("TOP ");
  84
  85             if (sqlGenerator.SqlVersion != SqlVersion.Sql8)
  86             {
  87                 writer.Write("(");
  88             }
  89
  90             this.TopCount.WriteSql(writer, sqlGenerator);
  91
  92             if (sqlGenerator.SqlVersion != SqlVersion.Sql8)
  93             {
  94                 writer.Write(")");
  95             }
  96
  97             writer.Write(" ");
  98
  99             if (this.WithTies)
 100             {
 101                 writer.Write("WITH TIES ");
 102             }
 103         }
 104
 105         #endregion
 106     }
 107 }