Move mysql check to the MySqlExpression .

Author: wuyou331

src/ServiceStack.OrmLite.MySql/MySqlExpression.cs

@@ -16,5 +16,10 @@ public override string ToDeleteRowStatement()
                 ? $"DELETE {DialectProvider.GetQuotedTableName(modelDef)} {FromExpression} {WhereExpression}"
                 : base.ToDeleteRowStatement();
         }
+
+        protected override string CreateInSubQuerySql(string quotedColName, string subSelect)
+        {
+            return $"{quotedColName} IN (SELECT * FROM ({subSelect})  SubQuery)";
+        }
     }
 }

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -2263,20 +2263,18 @@ protected string ConvertInExpressionToSql(MethodCallExpression m, object quotedC
                     var paramsRegex = new Regex(renameParams[i].Item1 + "([^\\d])");
                     subSelect = paramsRegex.Replace(subSelect, renameParams[i].Item2 + "$1");
                 }
-
-                if (DialectProvider.GetType().Name == "MySqlDialectProvider")
-                {
-                    return $"{quotedColName} IN (SELECT * FROM ({subSelect})  SubQuery)";
-                }
-                else
-                {
-                    return $"{quotedColName} IN ({subSelect})";
-                }
+                
+                return CreateInSubQuerySql(quotedColName, subSelect);
             }
 
             throw new NotSupportedException($"In({argValue.GetType()})");
         }
 
+        protected virtual string CreateInSubQuerySql(string quotedColName,string subSelect)
+        {
+            return $"{quotedColName} IN ({subSelect})";
+        }
+
         protected virtual object VisitColumnAccessMethod(MethodCallExpression m)
         {
             List<object> args = this.VisitExpressionList(m.Arguments);