java - Hibernate: how to use CONCAT and GROUP_CONCAT -
how can use concat()
, group_concat()
in hql queries?
about concat
: works same way in mysql (it concatenates strings, not aggregate function).
you can add group_concat
sql function configuration. way assume underlaying db knows function, , tie program mysql.
import org.hibernate.cfg.configuration; import org.hibernate.dialect.function.standardsqlfunction; import org.hibernate.type.stringtype; // ... myconf.addsqlfunction("group_concat", new standardsqlfunction("group_concat", new stringtype()));
you indicate output of function string. without when group_concat
numeric fields hibernate assume result numeric , crash.
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