Adding column in where condtion dynamically

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Adding column in where condtion dynamically

subramani.rudrappa 78855

SSC Eights!

Points: 848
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January 15, 2013 at 3:03 am

#272767

Hi,
I have following tables
product
customer
agent
we have column by name "state code" in product and customer.
i have sql like
select * from table name(we get table name dynamically like product,customer and agent using variable)
i need to add condition to get records with statecode=0
when i use where condition in the above query it looks like
select * from table name(we get table name dynamically like product,customer and agent)
where statecode=0
but this dynamic query fails for table "agent" as agent table does not contain statecode column.
so how can i wirte query where i get "where state code=0" condtion only for product and customer but not to agent.
mean
for product and customer query should look like this
select * from table name(we get table name dynamically like product,customer and agent)
where statecode=0
for agent :
select * from table name(we get table name dynamically like product,customer and agent)
i have tried
if (variable='product' or variable='customer')
select * from table name(we get table name dynamically like product,customer and agent)
where statecode=0
else
select * from table name(we get table name dynamically like product,customer and agent)
am looking at, is there any other way to implement this?

Viewing 7 posts - 1 through 6 (of 6 total)

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Kingston Dhasian SSCoach Points: 19799 More actions · Answer 1

You can implement this with Dynamic SQL as well

DECLARE@TableName VARCHAR(100), @sql VARCHAR(1000)

SET@TableName = 'agent'

SET@sql= ' SELECT* '

+ ' FROM ' + @TableName

+ ' WHERE ' + CASE WHEN @TableName IN ( 'product', 'customer' ) THEN 'statecode = 0' ELSE '1=1' END

EXECUTE ( @sql )

Kingston Dhasian

How to post data/code on a forum to get the best help - Jeff Moden
http://www.sqlservercentral.com/articles/Best+Practices/61537/

subramani.rudrappa 78855 SSC Eights! Points: 848 More actions · Answer 2

Hi Kingston Dhasian,

i implemented as per your inputs it is working as expected.

thank you!!!

DiverKas SSCrazy Points: 2049 More actions · Answer 3

You would be better served with the last line like this:

EXEC sp_executesql @sql

You should have a higher plan reuse rate instead of the standard EXECUTE (@SQL)

Sean Lange SSC Guru Points: 286590 More actions · Answer 4

Or even better create 3 stored procs to retrieve your data. You are using the "one query fits all via dynamic sql" approach. This is full of issues. It is difficult to maintain, once business rules start diverging you have really complicated code (this sounds the case here), you are running the risk of sql injection (maybe not now but in the future).

The code that Kingston shared will work but breaking this into separate pieces is really the best move in the long run.

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Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Sean Lange SSC Guru Points: 286590 More actions · Answer 5

DiverKas (1/15/2013)
You would be better served with the last line like this:
EXEC sp_executesql @sql
You should have a higher plan reuse rate instead of the standard EXECUTE (@SQL)

AND it allows for parameterization which is vital if using dynamic sql.

_______________________________________________________________

Need help? Help us help you.

Read the article at http://www.sqlservercentral.com/articles/Best+Practices/61537/ for best practices on asking questions.

Need to split a string? Try Jeff Modens splitter http://www.sqlservercentral.com/articles/Tally+Table/72993/.

Cross Tabs and Pivots, Part 1 – Converting Rows to Columns - http://www.sqlservercentral.com/articles/T-SQL/63681/
Cross Tabs and Pivots, Part 2 - Dynamic Cross Tabs - http://www.sqlservercentral.com/articles/Crosstab/65048/
Understanding and Using APPLY (Part 1) - http://www.sqlservercentral.com/articles/APPLY/69953/
Understanding and Using APPLY (Part 2) - http://www.sqlservercentral.com/articles/APPLY/69954/

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 6

I strongly recommend against this approach. It's a security risk and a maintenance nightmare. You wouldn't develop a C# method that could handle customers or products depending on a parameter passed, don't do it to SQL procedures.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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