Optimize the code

feat: 增加对PGSQL10及以上主键 IDENTITY 类型的支持，保持对默认实现 Serial 类型的兼容处理。

Src/Asp.NetCore2/SqlSugar/Abstract/ExecuteNavProvider/InsertNavProviderHelper.cs

@@ -200,7 +200,7 @@ namespace SqlSugar
                 {
                     foreach (var item in insertData)
                     {
-                        this._Context.Insertable(insertData).ExecuteCommandIdentityIntoEntity();
+                        this._Context.Insertable(item).ExecuteCommandIdentityIntoEntity();
                     }
                 }
                 else

Src/Asp.NetCore2/SqlSugar/Entities/ConnMoreSettings.cs

@@ -39,5 +39,6 @@ namespace SqlSugar
         public DbType? DatabaseModel { get;set; }
         public bool ClickHouseEnableFinal { get; set; }
         public bool EnableJsonb { get;  set; }
+        public PostgresIdentityStrategy PostgresIdentityStrategy { get; set; } = PostgresIdentityStrategy.Serial; // 兼容性处理，默认使用Serial
     }
 }

Src/Asp.NetCore2/SqlSugar/Enum/PostgresIdentityStrategy.cs

@@ -0,0 +1,14 @@
+namespace SqlSugar 
+{
+    public enum PostgresIdentityStrategy
+    {
+        /// <summary>
+        /// NEXTVAL() function
+        /// </summary>
+        Serial = 1,
+        /// <summary>
+        /// 自增长，PGSQL10+版本最佳实践
+        /// </summary>
+        Identity = 2
+    }
+}

Src/Asp.NetCore2/SqlSugar/Realization/PostgreSQL/DbMaintenance/PostgreSQLDbMaintenance.cs

@@ -485,6 +485,7 @@ WHERE tgrelid = '"+tableName+"'::regclass");
         {
             List<string> columnArray = new List<string>();
             Check.Exception(columns.IsNullOrEmpty(), "No columns found ");
+            var identityStrategy = this.Context.CurrentConnectionConfig.MoreSettings?.PostgresIdentityStrategy;
             foreach (var item in columns)
             {
                 string columnName = item.DbColumnName;
@@ -508,17 +509,26 @@ WHERE tgrelid = '"+tableName+"'::regclass");
                 string addItem = string.Format(this.CreateTableColumn, this.SqlBuilder.GetTranslationColumnName(columnName.ToLower(isAutoToLowerCodeFirst)), dataType, dataSize, nullType, primaryKey, "");
                 if (item.IsIdentity)
                 {
-                    if (dataType?.ToLower() == "int") 
+                    if(identityStrategy != PostgresIdentityStrategy.Identity)
                     {
-                        dataSize = "int4";
+                        if (dataType?.ToLower() == "int")
+                        {
+                            dataSize = "int4";
+                        }
+                        else if (dataType?.ToLower() == "long")
+                        {
+                            dataSize = "int8";
+                        }
+                        string length = dataType.Substring(dataType.Length - 1);
+                        string identityDataType = "serial" + length;
+                        addItem = addItem.Replace(dataType, identityDataType);
                     }
-                    else if (dataType?.ToLower() == "long")
+                    else  
                     {
-                        dataSize = "int8";
+                        string length = dataType.Substring(dataType.Length - 1);
+                        string identityDataType = "INT" + length + " GENERATED BY DEFAULT AS IDENTITY";
+                        addItem = addItem.Replace(dataType, identityDataType);
                     }
-                    string length = dataType.Substring(dataType.Length - 1);
-                    string identityDataType = "serial" + length;
-                    addItem = addItem.Replace(dataType, identityDataType);
                 }
                 columnArray.Add(addItem);
             }

Src/Asp.NetCore2/SqlSugar/Utilities/UtilMethods.cs

@@ -900,7 +900,8 @@ namespace SqlSugar
                     EnableILike=it.MoreSettings.EnableILike,
                     ClickHouseEnableFinal=it.MoreSettings.ClickHouseEnableFinal,
                     PgSqlIsAutoToLowerSchema=it.MoreSettings.PgSqlIsAutoToLowerSchema,
-                    EnableJsonb=it.MoreSettings.EnableJsonb
+                    EnableJsonb=it.MoreSettings.EnableJsonb,
+                    PostgresIdentityStrategy = it.MoreSettings.PostgresIdentityStrategy
 
                 },
                 SqlMiddle = it.SqlMiddle == null ? null : new SqlMiddle