Delphi: how to pass a list as a parameter to a SQL query?

Question

I have a list of integers or of strings and need to pass it as a parameter for a Delphi DataSet. How to do it?

Here is an example. MyQuery is something like:

Answer 1

There are several options for you but basically you need to get your values into a table. I would suggest a table variable for that.

Here is a version that unpacks an int list.

declare @IDs varchar(max)
set @IDs = :listParam

set @IDs = @IDs+','

declare @T table(ID int primary key)

while len(@IDs) > 1
begin
  insert into @T(ID) values (left(@IDs, charindex(',', @IDs)-1))
  set @IDs = stuff(@IDs, 1, charindex(',', @IDs), '')
end

select *
from myTable
where intKey in (select ID from @T)

It is possible to have multi-statement queries. The parameter :listParam should be a string:

MyQuery.ParamByName('listParam').AsString := '1,2,3';

You can use the same technique for strings. You just need to change the data type of ID to for instance varchar(10).

Instead of unpacking with a while loop you could make use of a split function

declare @T table(ID varchar(10))

insert into @T 
select s
from dbo.Split(',', :listParam)

select *
from myTable
where  charKey in (select ID from @T)

A string param could look like this:

MyQuery.ParamByName('listParam').AsString := 'Adam,Bertil,Caesar';