Mysql: How to select distinct values from a database column

Question

My goal is to select value from "EmbedImgDimension" column where in lots of duplicated values are present.

I have used the following query

select
  distinct EmbedImgId,
  VideoID,
  EmbedImgHeight,
  EmbedImgWidth,
  EmbedImgFileName,
  concat(embedimgwidth,' x ',embedimgheight) as EmbedImgDimension
  from embedimages
  inner join Video on Video.schoolid=#Value#
  where embedimages.isdeleted=0 order by embedimages.embedimgwidth asc;

wat modification should i make in this query so as to select unique values from the "EmbedImgDimension" column.Any help would be deeply appreciated.

Thanks.

Nicolas78 · Accepted Answer · 2010-08-05 10:06:50Z

3

  select
  distinct concat(embedimgwidth,' x ',embedimgheight) as EmbedImgDimension
  from embedimages
  inner join Video on Video.schoolid=#Value#
  where embedimages.isdeleted=0 order by embedimages.embedimgwidth asc;

update

saying you also want distinct video ids is a logical problem. you want to get a result in which each dimension appears only once, right? then, how can you expect to also get all the distinct videoID results? imagine you have

videoid  dimension
      1        1x1
      2        1x1
      3        2x2
      4        2x2

maybe you can tell me which result you'd like to get. but you're either going to get 1x1 and 2x2, or you're going to get 1,2,3,4 - the moment you want dimension uniqueness, you can't also get all the distinct videoids, see what I mean?

edited Aug 5, 2010 at 10:06

answered Aug 5, 2010 at 9:55

Nicolas78

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4 Comments

Nicolas78 Over a year ago

if you want to get distinct values, you have to remove the non-distinct values (like video_ids). the way you put it now, the database tries to find distinct combinations of video_id, EmbedImgId, and so on (which are probably unique so you won't get any groupings)

GethuJohn Over a year ago

@nicolas78: thanks pal... but i also need to implement select distinct EmbedImgId, VideoID, EmbedImgHeight, EmbedImgWidth, EmbedImgFileName in my query... so wat can be done...

Nicolas78 Over a year ago

check out my update. I think you want the logically impossible but maybe you can elaborate further

Nicolas78 Over a year ago

prly you just need several queries.

thelost · Accepted Answer · 2010-08-05 09:53:04Z

1

Use the distinct keyword on the EmbedImgDimension column.

answered Aug 5, 2010 at 9:53

thelost

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2 Comments

GethuJohn Over a year ago

can u explain to me the modification that has to be made in the current query

thelost Over a year ago

e.g. select distinct (concat ("test", col_name)) from table_name

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