Please assist with the query to find the extra records when creating table a and table b left join

Question

Hi ,

Please assist with the query to find the extra records when creating table a and table b left join. table a and table b both have more than one records.
Here is the script -

select a.[Fac],convert(varchar,b.fac_id + '-' + RIGHT('0000000000'+CAST(b.MRN AS VARCHAR(10)),10),50)
,surname+', '+given_names as name
from table1 a
left join table2 b
on a.[Fac] =convert(varchar,b.fac_id + '-' + RIGHT('0000000000'+CAST(b.MRN AS VARCHAR(10)),10),50)
order by a.[Fac]

The first table giving me 3277186 records . but when doing left join getting 3277290 record. My request is how to see the 104 records which is extra. Can someone help me with the query ?

Answer 1

Try as a possible query:

;with cte as (select a.[Fac],convert(varchar,b.fac_id + '-' + RIGHT('0000000000'+CAST(b.MRN AS VARCHAR(10)),10),50)
,surname+', '+given_names as name, count(*) over (partition by a.PK) as cntIds
from table1 a
left join table2 b
on a.[Fac] =convert(varchar,b.fac_id + '-' + RIGHT('0000000000'+CAST(b.MRN AS VARCHAR(10)),10),50))

select * from cte where cntIds > 1
order by [Fac]

Answer 2

Hi,@ASHMITP

Welcome to Microsoft T-SQL Q&A Forum!

Not tested, but you might try:

select *  
From  table2  
where not exists(  
select  table1.[Fac]  
from   table1  
where table1.[Fac]=convert(varchar,table2.fac_id + '-' + RIGHT('0000000000'+CAST(table2.MRN AS VARCHAR(10)),10),50)  
  
)  

Best regards,
Bert Zhou

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