33 lines
1.3 KiB
MySQL
33 lines
1.3 KiB
MySQL
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-- SCHEMA VERSION 7: 2020-06-12
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-- (in-db message count row)
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-- Add message count row to members table, initialize it with the correct data
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alter table members add column message_count int not null default 0;
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update members set message_count = (select count(*) from messages where messages.member = members.id);
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-- Create a trigger function to increment the message count on inserting to the messages table
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create function trg_msgcount_increment() returns trigger as $$
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begin
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update members set message_count = message_count + 1 where id = NEW.member;
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return NEW;
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end;
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$$ language plpgsql;
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create trigger increment_member_message_count before insert on messages for each row execute procedure trg_msgcount_increment();
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-- Create a trigger function to decrement the message count on deleting from the messages table
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create function trg_msgcount_decrement() returns trigger as $$
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begin
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-- Don't decrement if count <= zero (shouldn't happen, but we don't want negative message counts)
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update members set message_count = message_count - 1 where id = OLD.member and message_count > 0;
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return OLD;
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end;
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$$ language plpgsql;
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create trigger decrement_member_message_count before delete on messages for each row execute procedure trg_msgcount_decrement();
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-- (update schema ver)
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update info set schema_version = 7;
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