Synchronization code

Src/Asp.Net/SqlSugar/Abstract/CodeFirstProvider/CodeFirstProvider.cs

@@ -573,6 +573,10 @@ namespace SqlSugar
             {
                 return false;
             }
+            if (properyTypeName?.ToLower() == "varchar" && dataType?.ToLower() == "nvarchar")
+            {
+                return false;
+            }
             if (properyTypeName?.ToLower() == "number" && dataType?.ToLower() == "decimal")
             {
                 return false;

Src/Asp.Net/SqlSugar/Entities/ConnMoreSettings.cs

@@ -18,5 +18,6 @@ namespace SqlSugar
         public bool? TableEnumIsString { get; set; }
         public DateTime? DbMinDate { get; set; } = Convert.ToDateTime("1900-01-01");
         public bool IsNoReadXmlDescription { get;  set; }
+        public bool SqlServerCodeFirstNvarchar { get;  set; }
     }
 }

Src/Asp.Net/SqlSugar/Realization/SqlServer/DbMaintenance/SqlServerDbMaintenance.cs

@@ -321,6 +321,17 @@ namespace SqlSugar
         #endregion
 
         #region Methods
+        public override bool UpdateColumn(string tableName, DbColumnInfo column)
+        {
+            if (column.DataType != null && this.Context.CurrentConnectionConfig?.MoreSettings?.SqlServerCodeFirstNvarchar == true)
+            {
+                if (!column.DataType.ToLower().Contains("nvarchar"))
+                {
+                    column.DataType = column.DataType.ToLower().Replace("varchar", "nvarchar");
+                }
+            }
+            return base.UpdateColumn(tableName, column);
+        }
         public override bool IsAnyTable(string tableName, bool isCache = true)
         {
             if (tableName.Contains("."))
@@ -536,6 +547,14 @@ namespace SqlSugar
                     item.DecimalDigits = 4;
                     item.Length = 18;
                 }
+                else if (item.DataType != null && this.Context.CurrentConnectionConfig?.MoreSettings?.SqlServerCodeFirstNvarchar == true)
+                {
+                    if (!item.DataType.ToLower().Contains("nvarchar"))
+                    {
+                        item.DataType = item.DataType.ToLower().Replace("varchar", "nvarchar");
+                    }
+                }
+
             }
             string sql = GetCreateTableSql(tableName, columns);
             this.Context.Ado.ExecuteCommand(sql);

Src/Asp.Net/SqlSugar/Utilities/UtilMethods.cs

@@ -17,13 +17,6 @@ namespace SqlSugar
 {
     public class UtilMethods
     {
-        public static string ToUnderLineNew(string str)
-        {
-            if(!str.Contains("_"))
-               return string.Concat(str.Select((x, i) => i > 0 && char.IsUpper(x) ? "_" + x.ToString() : x.ToString()));
-            else
-            return str;
-        }
         public static string ToUnderLine(string str, bool isToUpper = false)
         {
             if (isToUpper)
@@ -181,7 +174,8 @@ namespace SqlSugar
                     TableEnumIsString = it.MoreSettings.TableEnumIsString,
                     DisableMillisecond = it.MoreSettings.DisableMillisecond,
                     DbMinDate=it.MoreSettings.DbMinDate,
-                    IsNoReadXmlDescription=it.MoreSettings.IsNoReadXmlDescription
+                    IsNoReadXmlDescription=it.MoreSettings.IsNoReadXmlDescription,
+                    SqlServerCodeFirstNvarchar=it.MoreSettings.SqlServerCodeFirstNvarchar
 
                 },
                 SqlMiddle = it.SqlMiddle == null ? null : new SqlMiddle