Optimized code

Src/Asp.NetCore2/SqlSugar/Abstract/UpdateProvider/UpdateableHelper.cs

@@ -678,11 +678,7 @@ namespace SqlSugar
                 var whereSql = Regex.Replace(sql, ".* WHERE ", "", RegexOptions.Singleline);
                 if (IsExists(sql))
                 {
-                    whereSql = Regex.Match(sql, @"\(EXISTS.+").Value;
-                    if (sql.Contains("((EXISTS")) 
-                    {
-                        whereSql = $"({whereSql}";
-                    }
+                    whereSql = UtilMethods.RemoveBeforeFirstWhere(sql);
                 }
                 dt = this.Context.Queryable<T>().Filter(null, true).Where(whereSql).AddParameters(parameters).ToDataTable();
             }

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

@@ -18,6 +18,18 @@ namespace SqlSugar
 {
     public class UtilMethods
     {
+        public static string RemoveBeforeFirstWhere(string query)
+        {
+            int whereIndex = query.IndexOf("WHERE", StringComparison.OrdinalIgnoreCase);
+            if (whereIndex >= 0)
+            {
+                return query.Substring(whereIndex + "WHERE".Length);
+            }
+            else
+            {
+                return query;
+            }
+        }
         public static List<object> ConvertToListOfObjects(object inValues)
         {
             // 创建一个新的List<object>并逐个将元素转换并添加到其中