UPDATE SQL 不同环境执行结果不一样

背景：1.前台：JQUERY 提交数据

           2.后台：OWIN C#  处理接收数据

　　　3.数据库： postgresql

============================================

问题描述：  后台接收到前台的数据，拼装一个 SQL 语句

update wbs_data 
set work_data='{"proName":"科研GOOD","proCode":"科研项目001","unitProName":"No1","drawingNo":"734116","proAddress":"大庆",
                 "partsComponents":"让胡路锅底",
                 "checkContent":"<p><br/>       这是一测试图片<img src="/upload/8096b2b7d0a20cf4cd425f7a7f094b36adaf995e.jpg" alt="" 
                 width="200" height="200" /> <br/></p>",
                 "checkOpinion":"检查意见：<br/>1.好<br/>2.很好<br/>3.非 常好","materialDocs":"原材料质量文件：<br/>1.测试文件1<br/>2.测试文件2",
                 "monitor":"","deputy":"","superEngineer":"","techLeader":"","date1":"","date2":"","date3":""}',work_state=1 
where pwbs_id=124

     我在后台C# 用 Npgsql执行时总是报错：invalid input syntax for type  json

public static string executeSQL(string strSQL)
        {
            Console.WriteLine("{0}", strSQL);
            string returnValue = string.Empty;
            NpgsqlConnection connection = new NpgsqlConnection(getConnectionString());
            NpgsqlCommand command = new NpgsqlCommand();
            command.Connection = connection;
            command.CommandText = strSQL;
            try
            {
                connection.Open();
                command.ExecuteNonQuery();
                //returnValue = "{"SUCCESS":"执行操作：'" + strSQL + "'成功！"}";
                Console.WriteLine("{0}","--------------------you are lucky----------------");
                returnValue = "{"SUCCESS":"操作成功！"}";

            }
            catch (Exception err)
            {
                returnValue = "{"ERROR":"发生以下错误：" + err.Message.ToString() + ""}";
            }
            finally
            {
                connection.Close();
            }
            return returnValue;
        }

奇怪的是，当我把这个拼装的SQL语句放在后台服务上PSQL 运行时，居然还通过了！

why??????

========================================================

经过测试发现：

我在获取生成JSON 串时，有个replace(/s/g, ' ')（JS代码中）没有加，而当我加上时就不再有这个问题

然而，另一位大神给出最本质的原因：

我在PSQL 中执行SQL ，实际是做了强制转化，而我在C# 中运行是没有经过处理的应该把SQL变成这样：

update tablename set column = value::json where id = _id;

即我上面的代码应该转化为：

update wbs_data 
set work_data='{"proName":"科研GOOD","proCode":"科研项目001","unitProName":"No1","drawingNo":"734116","proAddress":"大庆",
                 "partsComponents":"让胡路锅底",
                 "checkContent":"<p><br/>       这是一测试图片<img src="/upload/8096b2b7d0a20cf4cd425f7a7f094b36adaf995e.jpg" alt="" 
                 width="200" height="200" /> <br/></p>",
                 "checkOpinion":"检查意见：<br/>1.好<br/>2.很好<br/>3.非 常好","materialDocs":"原材料质量文件：<br/>1.测试文件1<br/>2.测试文件2",
                 "monitor":"","deputy":"","superEngineer":"","techLeader":"","date1":"","date2":"","date3":""}'::json,work_state=1 
where pwbs_id=124