sql表设计以获取具有多个包含和排除条件的记录

Question

We want to select customers based on following parameters ie customer should be in:

1. specific city ie cityId=1,2,3...

2. specific customerId should be excluded ie customerId=33,2323,34534...

3. specific age ie 5 years, 7 years, 72 years...

This inclusion & exclusion list can be any long.

How should we design database for this:

1. Create separate table 'customerInclusionCities' for these inclusion cities and do like:

select * from customers where cityId in (select cityId from customerInclusionCities)

Some we do for age, create table 'customerEligibleAge' with all entries of eligible age entries:

ie select * from customers where age in (select age from customerEligibleAge )

and Create separate table 'customerIdToBeExcluded' for excluding customers:

ie select * from customers where customerId not in (select customerId from customerIdToBeExcluded )

OR

2. Create One table with Category and Ids. ie Category1 for cities, Category2 for CustomerIds to be excluded.

Which approach is better, creating one table for these parameters OR creating separate tables for each list ie age, customerId, city?

Answer 1

If you use the database only that operation, I recommend to use the first solution. Also the first solution is very simple to deploy.

The second solution fills up with junk the DB.

Answer 2

IN ( SELECT ... ) can be very slow. Do your query as a single SELECT without subqueries. I assume all 3 columns are in the same table? (If not, that adds complexity.) The WHERE clause will probably have 3 IN ( constants ) clauses:

SELECT ...
    FROM tbl
    WHERE cityId IN (1,2,3...)
      AND customerId NOT IN (33,2323,34534...)
      AND age IN (5, 7, 72)

Have (at least):

INDEX(cityId),
INDEX(age)

(Negated things are unlikely to be able to use an index.)

The query will use one of the indexes; having both will give the Optimizer a choice of which it thinks is better.

Or...

SELECT c.*
    FROM customers AS c
    JOIN cityEligible AS b  ON b.city = c.city
    JOIN customerEligibleAge AS ce  ON c.age = ce.age
    LEFT JOIN customerIdToBeExcluded AS ex ON c.customerId = ex.customerId
    WHERE ex.customerId IS NULL

Suggested indexes (probably as PRIMARY KEY ):

customers: (city)
customerEligibleAge: (age)
customerIdToBeExcluded: (customerId)

In order to discuss further, please provide SHOW CREATE TABLE for each table and EXPLAIN SELECT ... for any of the queries actually work.