MySQL SELECT DISTINCT multiple columns

Question

Let s say I have columns a  b c  d in a table in a MySQL database  What I m trying to do is to select the distinct values of ALL of these 4 columns in my table  only the distinct values   I tried stuff like   SELECT DISTINCT a b c d FROM my table  SELECT DISTINCT a b c d FROM my table GROUP BY a b c d    None of those worked  Can anybody help out here   Thank you  NOTE I want the distinct values of the columns a  b  c d separately  Not the distinct combination of values

User · Answer

This will give DISTINCT values across all the columns   SELECT DISTINCT value FROM       SELECT DISTINCT a AS value FROM my table     UNION SELECT DISTINCT b AS value FROM my table     UNION SELECT DISTINCT c AS value FROM my table   AS derived

User · Answer

Another simple way to do it is with concat    SELECT DISTINCT CONCAT a b   AS cc FROM my table GROUP BY  cc

User · Answer

I know that the question is too old  anyway   select a  b from mytable group by a  b   will give your all the combinations

User · Answer

Taking a guess at the results you want so maybe this is the query you want then  SELECT DISTINCT a FROM my table UNION  SELECT DISTINCT b FROM my table UNION SELECT DISTINCT c FROM my table UNION SELECT DISTINCT d FROM my table

User · Answer

Both your queries are correct and should give you the right answer   I would suggest the following query to troubleshoot your problem   SELECT DISTINCT a b c d count    Count FROM my table GROUP BY a b c d order by count    desc   That is add count    field  This will give you idea how many rows were eliminated using the group command

User · Answer

can this help   select   SELECT group concat DISTINCT a  FROM my table  as a   SELECT group concat DISTINCT b  FROM my table  as b   SELECT group concat DISTINCT c  FROM my table  as c   SELECT group concat DISTINCT d  FROM my table  as d

[mysql] MySQL SELECT DISTINCT multiple columns

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