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To compare uncommon values in two tables

Posted on 2010-11-24
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Last Modified: 2012-05-10
Hi,
Suppose we have two tables both have a column CODE. Now we want to know what are the values that appear in CODE column of table 1 but are not present in CODE column of table 2. What should be the TSQL to find that?
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Question by:nkapur
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3 Comments
 
LVL 29

Accepted Solution

by:
Nightman earned 200 total points
ID: 34208551
Give this a bash.

SELECT * FROM Table1 as t1
WHERE
  NOT EXISTS
  (
    SELECT * FROM Table2 as t2 WHERE t2.CODE=t1.CODE
  )
0
 
LVL 26

Expert Comment

by:wilcoxon
ID: 34209271
Nightman has the right of it.  I would also recommend using select 1 rather than select * in the sub-query (usually very minimal performance impact but can be substantial if Table2 has wide rows).

SELECT * FROM Table1 as t1
WHERE
  NOT EXISTS
  (
    SELECT 1 FROM Table2 as t2 WHERE t2.CODE=t1.CODE
  )
0
 
LVL 29

Expert Comment

by:Nightman
ID: 34210375
normally wilcoxon would be correct about the select *, but in reality this a boolean expression and the value of * isn't evaluated, only the condtions.

You could even do the following with no divide by zero error:

SELECT * FROM Table1 as t1
WHERE
  NOT EXISTS
  (
    SELECT 1/0 FROM Table2 as t2 WHERE t2.CODE=t1.CODE
  )
0

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