如何在MySQL的字符串的第二个大写字母前插入空格？

Question

I have some data from a 3rd-party and one column is a concatenation of first and last name - but there is no space in between. My goal is to insert a space before the second capital letter, eg:

some_name
-------------
AdamPeterson
JohnSmith
StevenMulroy

Would become:

some_name
-------------
Adam Peterson
John Smith
Steven Mulroy

I know that this isn't foolproof, but it's the best it's going to get with the source data that I have.

I need to do this in SQL rather than Excel etc - because the data is refreshed regularly on the database level, and is then handled by another system without first being exported.

Any help is greatly appreciated!

Answer 1

For Mysql 8

SELECT REGEXP_REPLACE(CAST('JohnLexxxanon' as BINARY), '^([A-Z][a-z]+)([A-Z][a-z]+)$', '$1 $2');

For MariaDb 10+

SELECT REGEXP_REPLACE(CAST('JohnLexxxanon' as BINARY), '^([A-Z][a-z]+)([A-Z][a-z]+)$', '\\1 \\2');

Data is casted to binary to achieve case sensitivity.

This works for MySql 8 and MariaDb 10+

Answer 2

Here is a general query for all MySQL 5.1+ versions pretty sure it will also run on MariaDB.
The general idea is using a MySQL number generator to split the string into "tokens" and check the ascii range if the "token" is a capital letter or not

Query

SELECT 
   names.name   
 ,  INSERT (
       names.name 
     , LOCATE(
           SUBSTRING(names.name, number_generator.number, 1)  
         , names.name   
       )
     , 1
     , CONCAT(' ', SUBSTRING(names.name, number_generator.number, 1))
   ) AS changed_name
FROM (
  SELECT 
    @row := @row + 1 AS number 
  FROM (
    SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT   6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row1
  CROSS JOIN (
  SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) row2
CROSS JOIN (
  SELECT @row := 0 
) init_user_params 
) AS number_generator
CROSS JOIN 
 names 
WHERE
   number_generator.number > 1
 AND
   ASCII(SUBSTRING(names.name, number_generator.number, 1)) BETWEEN 65 AND 90

Result

| name         | changed_name  |
| ------------ | ------------- |
| AdamPeterson | Adam Peterson |
| JohnSmith    | John Smith    |
| StevenMulroy | Steven Mulroy |

see demo

Note

This query will not scale well on (very) large tables with millions or even billions of records because off the CROSS JOIN

Or you can use a tableless approach with

CROSS JOIN ( SELECT 'AdamPeterson' AS name UNION SELECT 'JohnSmith' UNION SELECT 'StevenMulroy' ) AS names

see that demo

Or use batches when you have big tables

CROSS JOIN ( SELECT name FROM names WHERE id >= 1 AND id <= 2 ORDER BY names.id ASC
) AS names

Why no LIMIT ? LIMIT is slow when using it with large offset numbers like LIMIT 1000000, 1000 . MySQL needs to fetch 1001000 records and drop 1000000 records again from a (disk in worst case scenario) temporary table

see that demo

Edited

it all looks like black magic to me! It is almost perfect - try the names 'AlexLafferty' or 'LaurenAnderson'. Maybe an off-by-one bug or something on the A? Thanks for all your help!

After a review i noticed that using LOCATE(..) in the INSERT(..) is pretty much redundant and can be removed to get it working properly.

So the patch is

SELECT 
    names.name   
 ,  INSERT (
       names.name 
     , number_generator.number
     , 1
     , CONCAT(' ', SUBSTRING(names.name, number_generator.number, 1))
   ) AS changed_name

see demo