mysql查询自增序列

select 
        (@i:=@i+1) as id,('2019041600000' + @i) as serial_id, 'CashLoan' as org_code, as out_user_code, as cust_code
    from customer_info ci
    inner join 
        (select DISTINCT(customerid) from business_contract) bc on = , (select @i:=0) as t;