How do I make an offset in this SQL Server 2000 query? - sql

Question

I wanna do an offset like: from 0 to 10000 records, from 10000 to 20000 records and so on. How do I modify this query to add an offset? Also, how can I improve this query for performance?
SELECT
CASE
WHEN c.DataHoraUltimaAtualizacaoILR >= e.DataHoraUltimaAtualizacaoILR AND c.DataHoraUltimaAtualizacaoILR >= t.DataHoraUltimaAtualizacaoILR THEN c.DataHoraUltimaAtualizacaoILR
WHEN e.DataHoraUltimaAtualizacaoILR >= c.DataHoraUltimaAtualizacaoILR AND e.DataHoraUltimaAtualizacaoILR >= t.DataHoraUltimaAtualizacaoILR THEN e.DataHoraUltimaAtualizacaoILR
WHEN t.DataHoraUltimaAtualizacaoILR >= c.DataHoraUltimaAtualizacaoILR AND t.DataHoraUltimaAtualizacaoILR >= e.DataHoraUltimaAtualizacaoILR THEN t.DataHoraUltimaAtualizacaoILR
ELSE c.DataHoraUltimaAtualizacaoILR
END AS 'updated_at',
p.Email,
c.ID_Cliente,
p.Nome,
p.DataHoraCadastro,
p.Sexo,
p.EstadoCivil,
p.DataNascimento,
getdate() as [today],
datediff (yy,p.DataNascimento,getdate()) as 'Idade',
datepart(month,p.DataNascimento) as 'MesAniversario',
e.Bairro,
e.Cidade,
e.UF,
c.CodLoja as codloja_cadastro,
t.DDD,
t.Numero
FROM
PessoaFisica p
LEFT JOIN
Cliente c ON (c.ID_Pessoa = p.ID_PessoaFisica)
LEFT JOIN
Loja l ON (CAST(l.CodLoja AS integer) = CAST(c.CodLoja AS integer))
LEFT JOIN
PessoaEndereco pe ON (pe.ID_Pessoa = p.ID_PessoaFisica)
LEFT JOIN
Endereco e ON (e.ID_Endereco = pe.ID_Endereco)
LEFT JOIN
PessoaTelefone pt ON (pt.ID_Pessoa = p.ID_PessoaFisica)
LEFT JOIN
Telefone t ON (t.ID_Telefone = pt.ID_Telefone)
WHERE
p.Email IS NOT NULL
AND p.Email <> ''
--and p.Email = 'aline.salles#uol.com.br'
GROUP BY
p.Email, c.ID_Cliente, p.Nome, p.EstadoCivil, p.DataHoraCadastro,
c.CodLoja, p.Sexo, e.Bairro, p.DataNascimento, e.Cidade, e.UF,
t.DDD, t.Numero, c.DataHoraUltimaAtualizacaoILR, e.DataHoraUltimaAtualizacaoILR,
t.DataHoraUltimaAtualizacaoILR
ORDER BY
updated_at DESC

Answer 1

Overall Process
If you have access to a more modern SQL Server version, then you could setup a process to copy the raw data to a new database on a daily basis. This might initially be an exact copy of the source database, just for staging the data. Then build an transformation process, using stored procedures or perhaps SSIS for high performance. That process would transform your data into your desired end state, and load it into the final database.
The copy process could be replication, but if your staging database is SQL Server 2005 or above, then you could also build a simple SSIS job to perform the copy. Run that job in a schedule task (SQL Agent) on a daily basis. You could combine the two - load data, then transform - but if using SSIS, then I recommend keeping these as separate SSIS packages, which will help with debugging problems. In the scheduled task you could run the two packages back-to-back.
Performance
You'll need good indexing on the table, but indexing alone is not sufficient. Casting CodLoja as an integer will prevent you from using indexes on that field. If you need to store those as strings for some other reason, then consider adding calculated columns,
ALTER TABLE xyz Add CodLojaAsInt as (CAST(CodLoja as int))
Then place an index on that new calculated column. The problem is that any function call in a ON or WHERE clause will cause SQL Server to scan the entire and convert every single row, instead of peaking into an index.

Answer 2

After searching and looking over my problem again, #sfuqua helped me with this solution. Basically I'll create some more organized tables in my local DB and get all the abstract/ugly data from the remote DB and process it locally to new tables.
I'm gonna use Elasticsearch to speed up the indexing and queries.

Answer 3

It sounds like you're trying to emulate MySQL's SELECT ... LIMIT X,Y feature. SQL Server doesn't have that. In SQL Server 2005+, you can use ROW_NUMBER() in a subquery. Since you're on 2000, however, you're going to have to do it one of the hard ways.
They way I've always done it is like this:
SELECT ... FROM Table WHERE PK IN
(SELECT TOP #PageSize PK FROM Table WHERE PK NOT IN
(SELECT TOP #StartRow PK FROM Table ORDER BY SortColumn)
ORDER BY SortColumn)
ORDER BY SortColumn
Although I recommend rewriting it to use EXISTS instead of IN and seeing which works better. You'll have to use EXISTS if you have compound primary keys.
That code and the other solutions are here.