From 44aea7795b300565bd74a41fee557d65c1a84a1e Mon Sep 17 00:00:00 2001
From: Christopher Jolly <chris-jolly_au@hotmail.com>
Date: Sat, 18 Feb 2023 10:23:14 +0800
Subject: [PATCH] Dual table: Auto detect the dual table name on model load.
 Use that table for any queries. Also allow a custom override name to be set

---
 src/EFCore.Jet.Data/JetConfiguration.cs         | 17 ++++++-----------
 .../Query/Sql/Internal/JetQuerySqlGenerator.cs  |  2 +-
 .../Internal/JetDatabaseModelFactory.cs         | 16 +++++++++++++++-
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/EFCore.Jet.Data/JetConfiguration.cs b/src/EFCore.Jet.Data/JetConfiguration.cs
index 314976e..6f0f2b5 100644
--- a/src/EFCore.Jet.Data/JetConfiguration.cs
+++ b/src/EFCore.Jet.Data/JetConfiguration.cs
@@ -57,18 +57,13 @@ namespace EntityFrameworkCore.Jet.Data
         /// <summary>
         /// The DUAL table or query
         /// </summary>
-        public static string DUAL { get; set; } = DUALForAccdb;
-
-        /// <summary>
-        /// The dual table for accdb
-        /// </summary>
-        public const string DUALForMdb = "(SELECT COUNT(*) FROM MSysRelationships)";
-
-        /// <summary>
-        /// The dual table for accdb
-        /// </summary>
-        public const string DUALForAccdb = "(SELECT COUNT(*) FROM MSysAccessStorage)";
+        public static string CustomDualTableName = "";
+        //MSysRelationships
+        //MSysAccessStorage
+        //#Dual
+        //(SELECT COUNT(*) FROM MSysAccessStorage)
 
+        public static string DetectedDualTableName = "#Dual";
         /// <summary>
         /// Gets or sets a value indicating whether show SQL statements.
         /// </summary>
diff --git a/src/EFCore.Jet/Query/Sql/Internal/JetQuerySqlGenerator.cs b/src/EFCore.Jet/Query/Sql/Internal/JetQuerySqlGenerator.cs
index ffa9e50..3f49a01 100644
--- a/src/EFCore.Jet/Query/Sql/Internal/JetQuerySqlGenerator.cs
+++ b/src/EFCore.Jet/Query/Sql/Internal/JetQuerySqlGenerator.cs
@@ -224,7 +224,7 @@ namespace EntityFrameworkCore.Jet.Query.Sql.Internal
         protected override void GeneratePseudoFromClause()
         {
             Sql.AppendLine()
-                .Append("FROM " + JetConfiguration.DUAL);
+                .Append("FROM " + "(SELECT COUNT(*) FROM `" + (string.IsNullOrEmpty(JetConfiguration.CustomDualTableName) ? JetConfiguration.DetectedDualTableName : JetConfiguration.CustomDualTableName) + "`)");
         }
 
         private void GenerateList<T>(
diff --git a/src/EFCore.Jet/Scaffolding/Internal/JetDatabaseModelFactory.cs b/src/EFCore.Jet/Scaffolding/Internal/JetDatabaseModelFactory.cs
index c0bd494..708b0c1 100644
--- a/src/EFCore.Jet/Scaffolding/Internal/JetDatabaseModelFactory.cs
+++ b/src/EFCore.Jet/Scaffolding/Internal/JetDatabaseModelFactory.cs
@@ -105,7 +105,21 @@ namespace EntityFrameworkCore.Jet.Scaffolding.Internal
                     table.Database = databaseModel;
                     databaseModel.Tables.Add(table);
                 }
-                
+
+                var tableNames = databaseModel.Tables.Select(t => t.Name).ToList();
+                if (tableNames.Contains("MSysAccessStorage"))
+                {
+                    JetConfiguration.DetectedDualTableName = "MSysAccessStorage";
+                }
+                else if (tableNames.Contains("MSysRelationships"))
+                {
+                    JetConfiguration.DetectedDualTableName = "MSysRelationships";
+                }
+                else if (tableNames.Contains("#Dual"))
+                {
+                    JetConfiguration.DetectedDualTableName = "#Dual";
+                }
+
                 return databaseModel;
             }
             finally