Migrating legacy code to 2008 R2 standards...

Question

Hi , I'm trying to rewrite the below code which uses tmp tables developed in 2000 version of SQL to 2008 R2 .any help in tuning query is appreciated.. -- Load all ip_id and skill combinations from tblSwDM_stg_SYNONYM into #temp_Complete_Skill_List
INSERT #temp_Complete_Skill_List
SELECT DISTINCT sm.switch_id, s.value, max(s.item_name), max(s.descr)
FROM tblSwDM_stg_SYNONYM s (NOLOCK)
INNER JOIN tblSwDM_SwitchMaster sm (NOLOCK)
ON s.cms_id = sm.cms_id
AND s.acd_no = sm.acd_number
WHERE s.item_type = 'split'
GROUP BY sm.switch_id, s.value
-- Append all additional ip_id and skill combinations from tblSwDM_stg_DSPLIT_UNIQUE into #temp_Complete_Skill_List
INSERT #temp_Complete_Skill_List
SELECT DISTINCT stg.ip_id, stg.split, NULL, NULL
FROM tblSwDM_stg_DSPLIT_UNIQUE stg (NOLOCK)
LEFT OUTER JOIN #temp_Complete_Skill_List tmp
ON stg.ip_id = tmp.switch_id
AND stg.split = tmp.skill
WHERE tmp.switch_id IS NULL
AND tmp.skill IS NULL
---- The above code will be later used to load the table below..
UPDATE tblSwDM_Dictionary
SET end_effective_date = @end_effective_date
FROM tblSwDM_Dictionary
INNER JOIN #temp_Updated_Skill ON tblSwDM_Dictionary.row_id = #temp_Updated_Skill.row_id
WHERE tblSwDM_Dictionary.end_effective_date IS NULL
INSERT INTO tblSwDM_Dictionary ([dictionary_type_id], [switch_id], [value], [name], [description], [start_effective_date])
SELECT DISTINCT dictionary_type_id, switch_id, skill, NULLIF(skill_name, ''), NULLIF(skill_description, ''), @start_effective_date
FROM #temp_Updated_Skill
Thank you ,
vishal.

Answer 1

>> I'm trying to rewrite the below code which uses TMP tables developed in 2000 version of SQL to 2008 R2<<
How much can you do to upgrade the schema? You have a ton of ISO-111798 violations in the data element names. For example, the prefix “tbl-' is absurdly redundant and it is called “tbling” as a design flaw.
We do not use temp tables in good SQL. This is how an old COBOL programmer fakes using a scratch tape instead of using a derived table, VIEW or CTE. You even do a step-by-step tape merge in SQL! 
DISTINCT and GROUP BY are seldom used together. But we have no DDL or other specs, so we do not know. The correct form is INSERT INTO; INSERT is dialect.
The use of NULLIF(skill_name, '') and NULL constant columns is usually a sign of bad design. How can the skill name be an empty string in a valid schema? Where is the explicit “unknown” value? Why create NULLs and then overwrite them in another process step?
(answer: This is how we did data processing with punch cards in the 1960's!)
The term “master” is not RDBMS; it is from tape files and network databases. 
Why do you have multiple names for the same data element? What is the generic, vague “value”? Generic vague “skill” (skill_name, skill_level, skill_code, etc), “split”? Likewise, there is no such thing as a “type_id” in RDBMS. Do you have a “blood_type” or
a “blood_type_id”? See the redundancy? People actually will say “blood_type_id_value” or worse. 
Did you know that the 1970's Sybase UPDATE..FROM.. does not work or port? Today we might use a MERGE statement. 
But my preference would be a 
CREATE VIEW Complete_Skill_List (switch_id, something_value, item_name, something_description)
so that it is always correct and current. It will also probably be faster than constantly doing disk seeks and updates. 
Any help?
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