sql - Selection of recurrence rules of recurring appointments -

sql - Selection of recurrence rules of recurring appointments -

i've got appointments 3 recurrence types: 1 = master appointment, 2 = regular appointment , 3 = exception. every recurring appointment has foreign key value references primary key of recurrence rule table. might master has been deleted , might 1 appointment recurring sequence of appointments specific rule left.

i want select distinct rows appointment relation/table foreign key primary key of rule-table not null (and need select columns of found rows). furthermore need query executable in relational databases (postgresql, mysql, ms-sql, derby...).

i want select 1 appointment each recurrence rule references rule, first 1 "lowest" start date.

probably it's simple select distinct recrule, * appointments i'm not sure if valid sql.

kind regards johannes

it sounds looking rules in reference table beingness used. if so:

select r.* recurrent r exists (select 1 appointments a.recurrentid = r.recurrentid );

this standard sql , should work in databases.

sql