如何从第二个连接表中获取 select 行，可以根据源列值的长度在 2 列中的任何一个上连接

Question

I have a lookup table that has names and corresponding 2 different codes a 9-digit one and a 11-character alpha-numeric one. The rows can be searched based on either of the 2 codes given depending on what the user selected while entering. So depending on whether the user has entered a 9-digit code or a 11-character alphanumeric code, I have to join the lookup table and accurately fetch the name.

Here's an example of the tables

Data table

+-----------+------------+
| code      | other cols |
+-----------+------------+
|112111213  | ...        |
|ABCD112233X| ...        |
|           |            |
+-----------+------------+

Lookup table

+---------+-----------+------------+
|code1    |code2      |name        |
+---------+-----------+------------+
|112111213|XXXX111111Z|Name 1      |
|000000000|ABCD112233X|Name 2      |
|         |           |            |
+---------+-----------+------------+

How can I get the result like below

+-----------+------------+
| code      | name       |
+-----------+------------+
|112111213  | Name 1     |
|ABCD112233X| Name 2     |
|           |            |
+-----------+------------+

Answer 1

Assuming that only either code1 or code2 would match in the join, you may try joining with OR logic:

UPDATE Data d
INNER JOIN Lookup l
    ON d.code = l.code1 OR d.code = l.code2
SET
    d.name = l.name;

Note that the presence of OR in the join condition might imply that your Lookup table is not properly normalized. Ideally, it might be better to maintain just a single code lookup column.

Edit:

I suggest refactoring your lookup table to the following:

+------------+-----------+
|code        |name       |
+------------+-----------+
|112111213   |Name 1     |
|XXXX111111Z |Name 1     |
|000000000   |Name 2     |
|ABCD112233X |Name 2     |
+------------+-----------+

Now you may simply perform a single join against the above code column and retrieve the name , assuming that a match be found. I am assuming that multiple matches would not occur. If they could, then you would need to add logic to handle that.

Answer 2

It can be code like this

SELECT t1.name, t2.code1 as code FROM data as t1
INNER JOIN Lookup as t2
    ON t1.code = t2.code1 
UNION ALL
SELECT t1.name, t2.code2 as code FROM data as t1
INNER JOIN Lookup as t2
    ON t1.code = t2.code2 

Answer 3

You can use or based join or you can use two separate query with union all .

Query 1: or based join

SELECT d.code, l.name 
FROM data_table  d
JOIN lookup_table l ON d.code = l.code1 OR d.code = l.code2;

Query 2: union all based join

SELECT d.code, l.name 
FROM data_table  d
JOIN lookup_table l ON d.code = l.code1
UNION ALL
SELECT d.code, l.name 
FROM data_table  d
JOIN lookup_table l ON d.code = l.code2; 

Note: Better use on index use union query.

PS: Based on @Tim you need to normalize the table.