如何使用dapper从数据库返回字符串

Question

I tried but it gives this error

Must declare the scalar variable "@imageid"

controller.cs

    [HttpGet]
    [Route("download/{id:int}")]
    public String Getfiles(int imageid)
    {

        return _ShopDataProvider.DownloadImage(imageid);

    }

class.cs

public String  DownloadImage(int imageid)
    {
        using(IDbConnection dbConnection = Connection)
        {

            string sQuery0 = "SELECT path FROM Shop WHERE ShopId = @imageid";
            dbConnection.Open();
            String Path = dbConnection.QueryFirstOrDefault<String>(sQuery0, new { ShopId = imageid });

            return Path;
        } 
    }

Answer 1

You're declaring a parameter in your SQL query named @imageid but not providing a value for it. You're providing a value for the parameter @ShopID ( new { ShopId = imageid } ), which your SQL query doesn't use.

Change new { ShopId = imageid } to new { imageid = imageid }

Please refer to the documentation .