THANKS Lucas.
Those are exactly the kind of tips I was looking for. I never thought of
assigning an alias to a local variable.
On Monday, May 6, 2019 at 10:30:33 AM UTC-5, Lukas Eder wrote:
>
> Hi Marty,
>
> I will be assuming that your query is already correct, so here are a few
> tips as to how you can simplify writing it. First off, I recommend
> assigning an aliased table to a local variable like this:
>
> Client root = CLIENT.as("root");
>
>
> This way, you can now dereference columns from the aliased table like this
> (your union all's first subquery):
>
> select(root.ID, root.NAME,
> root.PARENT_ID).from(root).where(root.ID.eq(clientId))
>
>
> The same is true for the CLIENT.as("child") table. Next, you can apply the
> same trick to your "clientlist" in order to dereference columns from it.
> The advantage of this approach is that your query will be less verbose and
> more type safe.
>
> Finally, since you're not really renaming any of the original columns, you
> can re-use the original columns to dereference columns from derived tables,
> such as
>
> cte.field(CLIENT.ID)
>
>
> This will dereference the "clientlist"."id" column, assuming it has the
> same type as CLIENT.ID
>
> I hope this helps,
> Lukas
>
> On Mon, May 6, 2019 at 3:08 PM <[email protected] <javascript:>> wrote:
>
>>
>> Thanks for your reply Lucas.
>>
>> I was able to eventually get something to work. Here is what I came up
>> with:
>>
>>
>> CommonTableExpression<Record3<Object, Object, Object>> cte =
>> name("clientlist").fields("id", "name", "parent_id").as(
>> select(field(name("root", "id")), field(name("root",
>> "name")), field(name("root", "parent_id"))).from(CLIENT.as("root"))
>> .where(field(name("root", "id")).eq(clientId))
>> .unionAll(
>> select(field(name("child", "id")),
>> field(name("child", "name")), field(name("child", "parent_id")))
>> .from(CLIENT.as("child"),
>> table("clientlist").as("parent"))
>> .where(
>> field(name("parent",
>> "id")).eq(field(name("child", "parent_id")))
>> .and(not(field(name("child",
>> "id")).eq(-1))))));
>>
>> Select<?> selectQuery =
>> dsl.withRecursive(cte).select(cte.field("id"),
>> cte.field("name"), cte.field("parent_id")).from(cte).orderBy(1);
>>
>> I would appreciate any advice on improvements you can suggest.
>>
>> Marty
>>
>>
>>
>>
>> On Monday, May 6, 2019 at 4:17:59 AM UTC-5, Lukas Eder wrote:
>>>
>>> Hi Marty,
>>>
>>> Thanks for your message. What are you struggling with specifically?
>>>
>>> Thanks,
>>> Lukas
>>>
>>> On Thu, May 2, 2019 at 6:35 PM <[email protected]> wrote:
>>>
>>>> All,
>>>>
>>>> I have been trying to construct DSL Select for the following SQL string:
>>>>
>>>> WITH RECURSIVE
>>>> clientlist (ID, NAME, PARENT_ID) AS
>>>> (
>>>> SELECT root.ID, root.NAME, root.PARENT_ID FROM ACP.CLIENT root
>>>> WHERE
>>>> root.ID = ?
>>>> UNION ALL
>>>> SELECT child.ID, child.NAME, child.PARENT_ID FROM ACP.CLIENT child,
>>>> clientlist parent
>>>> WHERE parent.ID = child.PARENT_ID AND NOT child.ID = -1
>>>> )
>>>> SELECT ID, NAME, PARENT_ID FROM clientlist ORDER BY 1
>>>>
>>>> and have been unable to do it.
>>>>
>>>> This is for a Postgres DB.
>>>>
>>>> (Assume the ACP.CLIENT table has columns ID (Integer), NAME
>>>> (varchar(64), PARENT_ID (Integer) )
>>>>
>>>> Any help will be greatly appreciated.
>>>>
>>>> Thanks,
>>>> Marty
>>>>
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