MySQL查询获取动态列及其值

Question

I've got a complex DB structure. I tried to solve it, but couldn't quite get it right.

I have five tables:

1. User table for getting office name and office_id
2. Service_list , which contains all service names
3. Service , which contains all service info based on office id
4. Service_trasaction , from which we get all services based on id ( service.service_id = service_transaction.id ).

Now I need output like this:

[office_name] [count recipients] [service_1] [service_2] .........
=======================================================================
Dhaka               5                4            2
Ctg                 0                5            0
Khulna              2                2            0

Currently, I'm only able to get office name and total recipients , using this query:

SELECT u.id, u.office_name, COUNT(r.id) AS `count`
FROM users u LEFT JOIN recipient r ON u.id = r.office_id
where(u.type = 'agency' and u.del_status = 0)
GROUP BY u.id, u.office_name;

Here is the structure of all the tables:

CREATE TABLE `recipient` (
  `id` int(10) NOT NULL,
  `name` varchar(100) NOT NULL,
  `gender` varchar(10) NOT NULL,
  `mobile` varchar(15) NOT NULL,
  `age` int(10) NOT NULL,
  `reg_no` varchar(10) NOT NULL,
  `address` varchar(255) NOT NULL,
  `disability_type` int(10) NOT NULL,
  `education` varchar(255) NOT NULL,
  `office_id` int(10) NOT NULL,
  `del_status` tinyint(1) NOT NULL,
  `create_date` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;      

 CREATE TABLE `users` (
  `id` tinyint(4) NOT NULL,
  `office_name` varchar(255) DEFAULT NULL,
  `district_id` int(10) DEFAULT NULL,
  `upazilla_id` int(10) DEFAULT NULL,
  `address` varchar(255) DEFAULT NULL,
  `mobile` varchar(11) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  `username` varchar(50) NOT NULL,
  `password` varchar(100) NOT NULL,
  `type` varchar(10) NOT NULL,
  `del_status` tinyint(1) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE `service` (
  `id` int(10) NOT NULL,
  `recipient_number` int(50) NOT NULL,
  `date` date NOT NULL,
  `office_id` int(10) NOT NULL,
  `del_status` tinyint(1) NOT NULL,
  `creation_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `service_list` (
  `id` int(3) NOT NULL,
  `service_name` varchar(50) NOT NULL,
  `del_status` tinyint(1) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `service_transaction` (
  `id` int(10) NOT NULL,
  `service_transaction_id` int(50) NOT NULL,
  `service_id` int(20) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

here is the sql dump file link : https://file.town/download/cez6u43ikr84by4xrzm34pjrf

Answer 1

It sounds like you're trying to pivot the results of an SQL query, or generate a matrix where one table creates the rows and the other creates the columns.

If both of the rows and columns are arbitrary lists, you can't do this. If the columns are an arbitrary list but the rows are fixed, you also can't do this in MySQL, as MySQL doesn't have a PIVOT function.

If there's a set number of columns thought that won't change (or the SQL statement can be edited every time one of those changes), then you can sort of do this by manually building up each of the columns from aggregate functions, but it gets really really messy in the query and you really have to think about what you're doing to achieve it.

In your specific example, something like this would be the approach for that:

SELECT
    office_name,
    COUNT(*) as count_recipients,
    SUM(service.id = 1) AS service_1,
    SUM(service.id = 2) AS service_2,
    ...
    SUM(service.id = n) AS service_n
FROM
    ...etc...
GROUP BY
    office_name

As you can see, you can't have it automatically create those service columns - you have to do one for each service.id. At best, your software could get the full list of all service id's, and programmatically build the query with a column for each service id, but there are limits to the number of columns you can return in a query, so this will only go so far.

Much better solution is to handle the display in your presentation code, not in the database query (as suggested by the delectably named Strawberry in the comments on your question above).