SQL How do I SELECT only the rows with a unique value on certain column

Question

Thanks a million everyone for everyone s response   Unfortunately  none of the solutions appear to be working on my end  and my guess is that the example I ve provided is messed up   So let me try again   My table looks like this       contract    project activity row1    1000    8000    10 row2    1000    8000    20 row3    1000    8001    10 row4    2000    9000    49 row5    2000    9001    49 row6    3000    9000    79 row7    3000    9000    78   Basically  the query I m looking for would return  2000 49  for  contract  activity  because only contract  2000 has one  and ONLY one  unique activity value   Again  thanks a million in advance  boroatel

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For MySQL   SELECT contract  activity FROM table GROUP BY contract HAVING COUNT DISTINCT activity    1

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Here is another option using sql servers count distinct   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78      SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1

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I m a fan of NOT EXISTS  SELECT DISTINCT contract  activity FROM table t1 WHERE NOT EXISTS     SELECT   FROM table t2   WHERE t2 contract   t1 contract AND t2 activity    t1 activity

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Updated to use your newly provided data   The solutions using the original data may be found at the end of this answer   Using your new data   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1   returns      2000  49  Solutions using original data  WARNING  The following solutions use the data previously given in the question and may not make sense for the current question   I have left them attached for completeness only   SELECT Col1  Count  col1   AS count FROM table  GROUP BY col1 HAVING count  gt  1   This should get you a list of all the values in col1 that are not distinct   You can place this in a table var or temp table and join against it   Here is an example using a sub-query   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  SELECT col1  col2 FROM  t WHERE col1 NOT IN       SELECT col1 FROM  t AS t GROUP BY col1 HAVING COUNT  col1    gt  1    This returns   D   E G   H   And another method that users a temp table and join   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  DROP TABLE  temp table   SELECT col1 INTO  temp table     FROM  t AS t GROUP BY col1 HAVING COUNT  col1     1  SELECT t col1  t col2 FROM  t AS t     INNER JOIN  temp table AS tt ON t col1   tt col1   Also returns   D   E G   H

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Sorry old post I know but I had the same issue  couldn t get any of the above to work for me  however I figured it out   This worked for me   SELECT DISTINCT  column As UniqueValues   FROM  db   dbo   table

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Updated to use your newly provided data   The solutions using the original data may be found at the end of this answer   Using your new data   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1   returns      2000  49  Solutions using original data  WARNING  The following solutions use the data previously given in the question and may not make sense for the current question   I have left them attached for completeness only   SELECT Col1  Count  col1   AS count FROM table  GROUP BY col1 HAVING count  gt  1   This should get you a list of all the values in col1 that are not distinct   You can place this in a table var or temp table and join against it   Here is an example using a sub-query   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  SELECT col1  col2 FROM  t WHERE col1 NOT IN       SELECT col1 FROM  t AS t GROUP BY col1 HAVING COUNT  col1    gt  1    This returns   D   E G   H   And another method that users a temp table and join   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  DROP TABLE  temp table   SELECT col1 INTO  temp table     FROM  t AS t GROUP BY col1 HAVING COUNT  col1     1  SELECT t col1  t col2 FROM  t AS t     INNER JOIN  temp table AS tt ON t col1   tt col1   Also returns   D   E G   H

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Modified   SELECT distinct contract  activity from  t a WHERE  SELECT COUNT DISTINCT activity  FROM  t b WHERE b contract   a contract    1   And here s another one -- shorter cleaner without subquery  select contract  max activity  from  t group by contract having count distinct activity    1

User · Answer

Here is another option using sql servers count distinct   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78      SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1

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Utilizing the  dynamic table  capability in SQL Server  querying against a parenthesis-surrounded query   you can return 2000  49 w  the following  If your platform doesn t offer an equivalent to the  dynamic table  ANSI-extention  you can always utilize a temp table in two-steps statement by inserting the results within the  dynamic table  to a temp table  and then performing a subsequent select on the temp table   DECLARE   T TABLE       contract  INT      project INT      activity INT    INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT      contract        Activity     max  activity  FROM           SELECT          contract            Activity      FROM          T     GROUP BY          contract            Activity        t GROUP BY      contract  HAVING count       1

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Updated to use your newly provided data   The solutions using the original data may be found at the end of this answer   Using your new data   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1   returns      2000  49  Solutions using original data  WARNING  The following solutions use the data previously given in the question and may not make sense for the current question   I have left them attached for completeness only   SELECT Col1  Count  col1   AS count FROM table  GROUP BY col1 HAVING count  gt  1   This should get you a list of all the values in col1 that are not distinct   You can place this in a table var or temp table and join against it   Here is an example using a sub-query   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  SELECT col1  col2 FROM  t WHERE col1 NOT IN       SELECT col1 FROM  t AS t GROUP BY col1 HAVING COUNT  col1    gt  1    This returns   D   E G   H   And another method that users a temp table and join   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  DROP TABLE  temp table   SELECT col1 INTO  temp table     FROM  t AS t GROUP BY col1 HAVING COUNT  col1     1  SELECT t col1  t col2 FROM  t AS t     INNER JOIN  temp table AS tt ON t col1   tt col1   Also returns   D   E G   H

User · Answer

Here is another option using sql servers count distinct   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78      SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1

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Sorry you re not using PostgreSQL     SELECT DISTINCT ON contract  activity   FROM thetable ORDER BY contract  activity  http   www postgresql org docs 8 3 static sql-select html SQL-DISTINCT  Oh wait   You only want values with exactly one     SELECT contract  activity  count    FROM thetable GROUP BY contract  activity HAVING count     1

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Assuming your table of data is called ProjectInfo   SELECT DISTINCT Contract  Activity     FROM ProjectInfo     WHERE Contract    SELECT Contract                           FROM  SELECT DISTINCT Contract  Activity                                     FROM ProjectInfo  AS ContractActivities                           GROUP BY Contract                           HAVING COUNT      1     The innermost query identifies the contracts and the activities   The next level of the query  the middle one  identifies the contracts where there is just one activity   The outermost query then pulls the contract and activity from the ProjectInfo table for the contracts that have a single activity   Tested using IBM Informix Dynamic Server 11 50 - should work elsewhere too

User · Answer

I m a fan of NOT EXISTS  SELECT DISTINCT contract  activity FROM table t1 WHERE NOT EXISTS     SELECT   FROM table t2   WHERE t2 contract   t1 contract AND t2 activity    t1 activity

User · Answer

Assuming your table of data is called ProjectInfo   SELECT DISTINCT Contract  Activity     FROM ProjectInfo     WHERE Contract    SELECT Contract                           FROM  SELECT DISTINCT Contract  Activity                                     FROM ProjectInfo  AS ContractActivities                           GROUP BY Contract                           HAVING COUNT      1     The innermost query identifies the contracts and the activities   The next level of the query  the middle one  identifies the contracts where there is just one activity   The outermost query then pulls the contract and activity from the ProjectInfo table for the contracts that have a single activity   Tested using IBM Informix Dynamic Server 11 50 - should work elsewhere too

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SELECT DISTINCT Contract  Activity FROM Contract WHERE Contract IN   SELECT Contract  FROM Contract GROUP BY Contract HAVING COUNT  DISTINCT Activity     1

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Try this   select           contract          max  activity   from          mytable  group by          contract  having          count  activity    1

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Try this   select           contract          max  activity   from          mytable  group by          contract  having          count  activity    1

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Sorry old post I know but I had the same issue  couldn t get any of the above to work for me  however I figured it out   This worked for me   SELECT DISTINCT  column As UniqueValues   FROM  db   dbo   table

User · Answer

SELECT DISTINCT Contract  Activity FROM Contract WHERE Contract IN   SELECT Contract  FROM Contract GROUP BY Contract HAVING COUNT  DISTINCT Activity     1

User · Answer

Sorry you re not using PostgreSQL     SELECT DISTINCT ON contract  activity   FROM thetable ORDER BY contract  activity  http   www postgresql org docs 8 3 static sql-select html SQL-DISTINCT  Oh wait   You only want values with exactly one     SELECT contract  activity  count    FROM thetable GROUP BY contract  activity HAVING count     1

User · Answer

I m a fan of NOT EXISTS  SELECT DISTINCT contract  activity FROM table t1 WHERE NOT EXISTS     SELECT   FROM table t2   WHERE t2 contract   t1 contract AND t2 activity    t1 activity

User · Answer

Utilizing the  dynamic table  capability in SQL Server  querying against a parenthesis-surrounded query   you can return 2000  49 w  the following  If your platform doesn t offer an equivalent to the  dynamic table  ANSI-extention  you can always utilize a temp table in two-steps statement by inserting the results within the  dynamic table  to a temp table  and then performing a subsequent select on the temp table   DECLARE   T TABLE       contract  INT      project INT      activity INT    INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT      contract        Activity     max  activity  FROM           SELECT          contract            Activity      FROM          T     GROUP BY          contract            Activity        t GROUP BY      contract  HAVING count       1

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Updated to use your newly provided data   The solutions using the original data may be found at the end of this answer   Using your new data   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1   returns      2000  49  Solutions using original data  WARNING  The following solutions use the data previously given in the question and may not make sense for the current question   I have left them attached for completeness only   SELECT Col1  Count  col1   AS count FROM table  GROUP BY col1 HAVING count  gt  1   This should get you a list of all the values in col1 that are not distinct   You can place this in a table var or temp table and join against it   Here is an example using a sub-query   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  SELECT col1  col2 FROM  t WHERE col1 NOT IN       SELECT col1 FROM  t AS t GROUP BY col1 HAVING COUNT  col1    gt  1    This returns   D   E G   H   And another method that users a temp table and join   DECLARE  t TABLE  col1 VARCHAR 1   col2 VARCHAR 1   col3 VARCHAR 1     INSERT INTO  t VALUES   A    B    C     INSERT INTO  t VALUES   D    E    F     INSERT INTO  t VALUES   A    J    K     INSERT INTO  t VALUES   G    H    H      SELECT   FROM  t  DROP TABLE  temp table   SELECT col1 INTO  temp table     FROM  t AS t GROUP BY col1 HAVING COUNT  col1     1  SELECT t col1  t col2 FROM  t AS t     INNER JOIN  temp table AS tt ON t col1   tt col1   Also returns   D   E G   H

User · Answer

Try this   select           contract          max  activity   from          mytable  group by          contract  having          count  activity    1

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SELECT DISTINCT Contract  Activity FROM Contract WHERE Contract IN   SELECT Contract  FROM Contract GROUP BY Contract HAVING COUNT  DISTINCT Activity     1

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For MySQL   SELECT contract  activity FROM table GROUP BY contract HAVING COUNT DISTINCT activity    1

User · Answer

Modified   SELECT distinct contract  activity from  t a WHERE  SELECT COUNT DISTINCT activity  FROM  t b WHERE b contract   a contract    1   And here s another one -- shorter cleaner without subquery  select contract  max activity  from  t group by contract having count distinct activity    1

User · Answer

Assuming your table of data is called ProjectInfo   SELECT DISTINCT Contract  Activity     FROM ProjectInfo     WHERE Contract    SELECT Contract                           FROM  SELECT DISTINCT Contract  Activity                                     FROM ProjectInfo  AS ContractActivities                           GROUP BY Contract                           HAVING COUNT      1     The innermost query identifies the contracts and the activities   The next level of the query  the middle one  identifies the contracts where there is just one activity   The outermost query then pulls the contract and activity from the ProjectInfo table for the contracts that have a single activity   Tested using IBM Informix Dynamic Server 11 50 - should work elsewhere too

User · Answer

Modified   SELECT distinct contract  activity from  t a WHERE  SELECT COUNT DISTINCT activity  FROM  t b WHERE b contract   a contract    1   And here s another one -- shorter cleaner without subquery  select contract  max activity  from  t group by contract having count distinct activity    1

User · Answer

Try this   select           contract          max  activity   from          mytable  group by          contract  having          count  activity    1

User · Answer

Utilizing the  dynamic table  capability in SQL Server  querying against a parenthesis-surrounded query   you can return 2000  49 w  the following  If your platform doesn t offer an equivalent to the  dynamic table  ANSI-extention  you can always utilize a temp table in two-steps statement by inserting the results within the  dynamic table  to a temp table  and then performing a subsequent select on the temp table   DECLARE   T TABLE       contract  INT      project INT      activity INT    INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT      contract        Activity     max  activity  FROM           SELECT          contract            Activity      FROM          T     GROUP BY          contract            Activity        t GROUP BY      contract  HAVING count       1

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Assuming your table of data is called ProjectInfo   SELECT DISTINCT Contract  Activity     FROM ProjectInfo     WHERE Contract    SELECT Contract                           FROM  SELECT DISTINCT Contract  Activity                                     FROM ProjectInfo  AS ContractActivities                           GROUP BY Contract                           HAVING COUNT      1     The innermost query identifies the contracts and the activities   The next level of the query  the middle one  identifies the contracts where there is just one activity   The outermost query then pulls the contract and activity from the ProjectInfo table for the contracts that have a single activity   Tested using IBM Informix Dynamic Server 11 50 - should work elsewhere too

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For MySQL   SELECT contract  activity FROM table GROUP BY contract HAVING COUNT DISTINCT activity    1

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SELECT DISTINCT Contract  Activity FROM Contract WHERE Contract IN   SELECT Contract  FROM Contract GROUP BY Contract HAVING COUNT  DISTINCT Activity     1

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SELECT DISTINCT Col1 Col2 FROM Table GROUP BY Col1 HAVING COUNT  DISTINCT Col1     1

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I m a fan of NOT EXISTS  SELECT DISTINCT contract  activity FROM table t1 WHERE NOT EXISTS     SELECT   FROM table t2   WHERE t2 contract   t1 contract AND t2 activity    t1 activity

User · Answer

For MySQL   SELECT contract  activity FROM table GROUP BY contract HAVING COUNT DISTINCT activity    1

User · Answer

Here is another option using sql servers count distinct   DECLARE   T TABLE   contract  INT  project INT  activity INT   INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78      SELECT DISTINCT  contract   activity FROM  T AS A WHERE      SELECT COUNT  DISTINCT activity         FROM  T AS B WHERE B  contract    A  contract     1

User · Answer

SELECT DISTINCT Col1 Col2 FROM Table GROUP BY Col1 HAVING COUNT  DISTINCT Col1     1

User · Answer

Utilizing the  dynamic table  capability in SQL Server  querying against a parenthesis-surrounded query   you can return 2000  49 w  the following  If your platform doesn t offer an equivalent to the  dynamic table  ANSI-extention  you can always utilize a temp table in two-steps statement by inserting the results within the  dynamic table  to a temp table  and then performing a subsequent select on the temp table   DECLARE   T TABLE       contract  INT      project INT      activity INT    INSERT INTO  T VALUES  1000     8000     10   INSERT INTO  T VALUES  1000     8000     20   INSERT INTO  T VALUES  1000     8001     10   INSERT INTO  T VALUES  2000     9000     49   INSERT INTO  T VALUES  2000     9001     49   INSERT INTO  T VALUES  3000     9000     79   INSERT INTO  T VALUES  3000     9000     78    SELECT      contract        Activity     max  activity  FROM           SELECT          contract            Activity      FROM          T     GROUP BY          contract            Activity        t GROUP BY      contract  HAVING count       1

User · Answer

Modified   SELECT distinct contract  activity from  t a WHERE  SELECT COUNT DISTINCT activity  FROM  t b WHERE b contract   a contract    1   And here s another one -- shorter cleaner without subquery  select contract  max activity  from  t group by contract having count distinct activity    1

User · Answer

Sorry you re not using PostgreSQL     SELECT DISTINCT ON contract  activity   FROM thetable ORDER BY contract  activity  http   www postgresql org docs 8 3 static sql-select html SQL-DISTINCT  Oh wait   You only want values with exactly one     SELECT contract  activity  count    FROM thetable GROUP BY contract  activity HAVING count     1

User · Answer

Sorry you re not using PostgreSQL     SELECT DISTINCT ON contract  activity   FROM thetable ORDER BY contract  activity  http   www postgresql org docs 8 3 static sql-select html SQL-DISTINCT  Oh wait   You only want values with exactly one     SELECT contract  activity  count    FROM thetable GROUP BY contract  activity HAVING count     1

[sql-server] SQL: How do I SELECT only the rows with a unique value on certain column?

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