mostlymatter/server/channels/db/migrations/mysql/000089_add-channelid-to-reaction.down.sql

SET @preparedStatement = (SELECT IF(
    EXISTS(
        SELECT 1 FROM INFORMATION_SCHEMA.STATISTICS
        WHERE table_name = 'Reactions'
        AND table_schema = DATABASE()
        AND column_name = 'ChannelId'
    ) > 0,
    'ALTER TABLE Reactions DROP COLUMN ChannelId;',
    'SELECT 1;'
));

PREPARE removeColumnIfExists FROM @preparedStatement;
EXECUTE removeColumnIfExists;
DEALLOCATE PREPARE removeColumnIfExists;