I'm a new baby in Dapper. Trying to incorporate CRUD operations with Dapper and Dapper.SimpleCRUD lib. Here is the sample code...  

My Data Model Looks like

```
Class Product
{
  public string prodId {get;set;}
  public string prodName {get;set;}
  public string Location {get;set;}
}

```

Dapper Implementation - Insert

```
public void Insert(Product item)
{
    using(var con = GetConnection())
    {
      con.Insert(item);
    }
}

```

Since the ProdId in the Db is an Identity Column it fails. How does it indicate ProdId is an Identity Column in DB?

Dapper Implementation - Get

```
public IEnumerable<Product> GetAll()
{
        IEnumerable<Product> item = null;
        using (var con = GetConnection())
        {
            item = con.GetList<Product>();
        }
        return item;
}

```

It gives an exception:

> 
> "Entity must have at least one [Key] property"!
> 
> 
>
['https://Stackoverflow.com/questions/33264891', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/2066540/']
This is happening since you are using a Dapper Extension, which has implemented the `Insert` CRUD extension method. Ideally this can be achieved using simple

`con.Execute` in the Dapper, but since you want to pass an object and create an insert query automatically by the extension, you need to help it understand, which is the Primary Key for the given product entity, following modification shall help:

```
[Key]
public string prodId {get;set;}

```

where Key attribute shall be either implemented in `Dapper Extension` or the `Component Model`.

Alternatively you may rename `prodId` to `Id`, which will automatically make it the key. Also check the following [link](http://rnsx.co.uk/an-introduction-to-dapper-extensions/), where you can create a separate mapper for the entity, thus defining the key, whatever works in your case
Connecting to SQL Server 2016, I had this error with both Dapper.Contrib & Dapper.SimpleCRUD when I forgot to attach the Primary Key to the Id column of the table. 

Primary Key added to the table, project rebuilt & published to clear cache and all is good with both [Key] & [ExplicitKey] ( the latter in DapperContrib).