SQL query to translate a list of numbers matched against several ranges, to a list of values

问题

I need to convert a list of numbers that fall within certain ranges into a list of values, ordered by a priority column. The table has the following values:

| YEAR | R_MIN |  R_MAX | VAL | PRIO |
------------------------------------
  2010   18000    90100   52    6
  2010  240000   240099   82    3
  2010  250000   259999   50    5
  2010  260000   260010   92    1
  2010  330000   330010   73    4
  2010  330011   370020   50    5
  2010  380000   380050   84    2

The ranges will be different for different years. The ranges within one year will never overlap.

The input will be a year and a list of numbers that might fall within one these ranges. The list of input number will be small, 1 to 10 numbers. Example of input numbers:

(20000, 240004, 375000, 255000)

With that input I would like to get a list ordered by the priority column, or a single value:

82
50
52

The only value I'm interested in here is 82, so UNIQUE and MAX_RESULTS=1 would do. It can easily be done with one query per number, and then sorting it in the Java code, but I would prefer to do it in a single SQL query.

What SQL query, to be run in an Oracle database, would give me the desired result?

(Note, this is not about splitting an input string, it's about matching each value in a list of values to ranges defined in different columns.)

回答1:

I am guessing you want to pass that set of numbers as a string and split into into individual numbers. This is harder than you might think, because Oracle doesn't come with a built-in tokenizer. Weird, huh?

There are a number of PL/SQL tokenizer solutions knocking around Das Interwabs. I am using a variant of Anup Pani's implementation, which uses Regex (hence only Oracle 10g or higher). My variant returns an array of numbers which I have declared as a SQL type:

SQL> create or replace type numbers as table of number
  2  /

Type created.

SQL>

This means I can use it as an input to a TABLE() function in a SELECT statement:

SQL> select * from table (str_to_number_tokens('20000, 240004, 375000, 255000'))
  2  /

COLUMN_VALUE
------------
       20000
      240004
      375000
      255000

SQL>

This means I can turn your string of numbers into a table which I can join to in a query, like this:

SQL> select val
  2  from t23
  3       , ( select column_value as i_no
  4           from table (str_to_number_tokens('20000, 240004, 375000, 255000')) ) sq
  5  where t23.year = 2010
  6  and   sq.i_no between t23.r_min and t23.r_max
  7  order by t23.priority
  8  /

       VAL
----------
        82
        50
        52

SQL>

回答2:

I think your first task would be to convert the list of numbers into a result set (ie. in-memory table) that you can join to. I don't know Oracle, so there may be an easy way to do it, but if not you'll need to write some kind of user-defined function that does this. It shouldn't be too hard and performance is not an issue since the list is small. You can then do a join to that table. Something like this:

SELECT yt.val
FROM your_table yt
JOIN your_parse_numbers_function(@inputlist) il
ON il.value >= yt.R_MIN AND il.value <= yt.R_MAX
WHERE yt.YEAR = @year

You could limit that to 1 result if you wish, but if your assumption about ranges not overlapping is correct then it should only return 1 anyway.

来源：https://stackoverflow.com/questions/2635930/sql-query-to-translate-a-list-of-numbers-matched-against-several-ranges-to-a-li

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sql

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tokenize