rewrite sql where empty array parameter.

[fredliex]

Code

var result = connection.ExecuteQuery("SELECT * FROM [sc].[IdentityTable] WHERE ColumnInt IN (@ColumnInt);", 
      new { ColumnInt = new int[0] });

Exception

Microsoft.Data.SqlClient.SqlException
  HResult=0x80131904
  Message=Must declare the scalar variable "@ColumnInt"。
  Source=Core Microsoft SqlClient Data Provider
  StackTrace: 
   at Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) in /_/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlConnection.cs:line 1858

Command watch

command.CommandText = "SELECT * FROM [sc].[IdentityTable] WHERE ColumnInt IN (@ColumnInt);"
command.Parameters (count = 0)

Revise

When the parameter is an empty set, replace @arg with (select @arg where 1 = 0).
And set a DbNull parameter in command.Parameters.

Example

-- @normal = new[] { 1, 2 }
-- @empty = @emptyA = @emptyB = new int[0]
where id in (@normal)		--> where id in (@normal0, @normal1)
where id in (@empty)		--> where id in ((select @empty where 1 = 0))
where id in (@empty, @normal)	--> where id in ((select @empty where 1 = 0), @normal0, @normal1)
where id in (@emptyA, @emptyB)	--> where id in ((select @emptyA where 1 = 0), (select @emptyB where 1 = 0))

[fredliex]

select * from someTable where id in ((select 3 where 1 = 0), 1, 2)

The above syntax has been tested in databases:

• ms sql : my local machine
• sqlite: https://extendsclass.com/sqlite-browser.html
• mysql: https://extendsclass.com/mysql-online.html
• postgresql: https://extendsclass.com/postgresql-online.html

[mikependon]

Just a small comment, let us make all the SQL statement UPPERCASE like SELECT * FROM Table WHERE 1 = 0;.

[mikependon]

Thank you for this PR, you are really maturing and expanding the capability of this ORM. 🛩️ This PR is great and we need to update the documentation here, feel free to put it there, otherwise, I can also put it there soon.

Please continue to do this and I am happy to really shout you out in Twitter and to any other social media if you have an account there!

[mikependon]

A small question from me 😄, why did not you just make a little hack here?

-- @normal = new[] { 1, 2 }
-- @empty = @emptyA = @emptyB = new int[0]
where id in (@normal)		--> where id in (@normal0, @normal1)
where id in (@empty)		--> where 1 = 0 // Only if all the passed parameters are null or empty
where id in (@empty, @normal)	--> where id in (@normal0, @normal1) // ignoring the empty
where id in (@emptyA, @emptyB)	--> where 1 = 0 // Only if all the passed parameters are null or empty

Just a small thoughts. But TBH, the code change you made is very minimal, so it will merge it in a while.

[fredliex]

I have pushed a commit to change uppercase.

[fredliex]

A small question from me 😄, why did not you just make a little hack here?

-- @normal = new[] { 1, 2 }
-- @empty = @emptyA = @emptyB = new int[0]
where id in (@normal)		--> where id in (@normal0, @normal1)
where id in (@empty)		--> where 1 = 0 // Only if all the passed parameters are null or empty
where id in (@empty, @normal)	--> where id in (@normal0, @normal1) // ignoring the empty
where id in (@emptyA, @emptyB)	--> where 1 = 0 // Only if all the passed parameters are null or empty

Just a small thoughts. But TBH, the code change you made is very minimal, so it will merge it in a while.

Because such a processing method will be very simple, just replace @empty.
If want to change it to where 1 = 0, we need to analyze the context of sql, and the processing logic will become very complicated.

[mikependon]

That makes sense and based on your changes, it is very minimal. Thanks for your contributions as always.