SQL DISTINCT value within a field - sql

Question

I know how to select distinct rows, but I can't find how to extract distinct 'words/string/data' from a field to update another column.
For example, if I have data in a table like so..
Table 1
ID TEXTDATA
123 ROCK DANCE ROCK INDIE ROCK POP DISCO EURO POP
456 POP DANCE DISCO POP
I want to UPDATE another field in another table with 'distinct' data from within the TEXTDATA fields, so it would look like this
Table 2
ID NEWTEXTDATA
123 ROCK DANCE INDIE POP DISCO EURO
456 POP DANCE DISCO
I worked out how to Update one table with data from another...
UPDATE table2 JOIN table1 ON table2.ID = table1.ID SET table2.NEWTEXTDATA = table1.TEXTDATA;
But I want it to be of distinct values within the TEXTDATA records. Hope that makes some sort of sense. Is that possible to do within an update query?
Many thanks in advance

Answer 1

For Sql Server 2008:
You can do this by using the xml query with distinct values. The below code will give you the distinct records from given row.
cast(cast('<d>'+replace(TEXTDATA, ' ','</d><d>')+'</d>' as xml).query('distinct-values(/d)') as varchar(max))
So with the help of above function your final query will be something like below.
UPDATE
table2
SET
NEWTEXTDATA = cast(cast('<d>'+replace(TEXTDATA, ' ','</d><d>')+'</d>' as xml).query('distinct-values(/d)') as varchar(max))
FROM
table2 t2
JOIN
table1 t1
ON
t2.ID = t1.ID;
Here is the working SQLFiddle for same.
For MySql: There is no way in MySql to achieve this.
Normalize your database.
get values from table and use php explode() , and use array_unique to remove duplicate values.