Hi,

At least remove the distinct from the EXISTS predicate.

AFAIU your query you could also merge the exists into the "base" from.
Or move "contskill t1" also to the EXISTS and the DISTINCT can be removed at both places.

SELECT DISTINCT
c.contid, c.surname, c.forename, c.dob,
c.postcode, c.filed, c.available, c.email
FROM
cont c
JOIN contskill t1 ON (t1.contid = c.contid AND t1.skillid = 10)
JOIN contskill t2 ON (t2.contid = c.contid AND t2.skillid = 17)
JOIN contskill t3 ON (t3.contid = c.contid AND t3.skillid = 18)
JOIN contskill t4 ON (t4.contid = c.contid AND t4.skillid = 22)
JOIN contskill t5 ON (t5.contid = c.contid AND t5.skillid = 24)
JOIN contskill t6 ON (t6.contid = c.contid AND t6.skillid = 29)
JOIN contskill t7 ON (t7.contid = c.contid AND t7.skillid = 30)
JOIN contskill t8 ON (t8.contid = c.contid AND t8.skillid = 34)
JOIN contskill t9 ON (t9.contid = c.contid AND t9.skillid = 4209)
JOIN contskill t10 ON (t10.contid = c.contid AND t10.skillid = 62)


SELECT
c.contid, c.surname, c.forename, c.dob,
c.postcode, c.filed, c.available, c.email
FROM
cont c
WHERE
EXISTS(
SELECT 1 FROM
contskill t1
JOIN contskill t2 ON (t2.contid = c.contid AND t2.skillid = 17)
JOIN contskill t3 ON (t3.contid = c.contid AND t3.skillid = 18)
JOIN contskill t4 ON (t4.contid = c.contid AND t4.skillid = 22)
JOIN contskill t5 ON (t5.contid = c.contid AND t5.skillid = 24)
JOIN contskill t6 ON (t6.contid = c.contid AND t6.skillid = 29)
JOIN contskill t7 ON (t7.contid = c.contid AND t7.skillid = 30)
JOIN contskill t8 ON (t8.contid = c.contid AND t8.skillid = 34)
JOIN contskill t9 ON (t9.contid = c.contid AND t9.skillid = 4209)
JOIN contskill t10 ON (t10.contid = c.contid AND t10.skillid = 62)
WHERE
t1.contid = c.contid AND t1.skillid = 10)

Regards,
Arno Brinkman
ABVisie

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