MySQL create columns out of rows on the fly - mysql

Question

My issue is that I have a table apidata that holds multiple rows of data for each domain. So when I query apidata I naturally get multiple rows as a result. Is there any way to turn those rows into columns? I ask because I'm already using a query to pull the domain data (page title, URL, top level domain, ip address etc) and I need to add the api data with it. I believe I have to do this in two queries but I would love to at least have one row per domain to make the query and loop as fast a possible.
So the question is, can I create columns out of rows on the fly?
Heres a SQL Fiddle => http://sqlfiddle.com/#!2/8e408/4
(Note, I didnt put the whole database in the fiddle just the tables that effect the query. If you think somethings missing that you need, let me know.)
Tool_Runs (id_sha is the main lookup value for tool runs)
| ID | ID_SHA |
+----+------------------------------------------+
| 1 | 68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A |
Domains (Run_id is FK to tool_runs.id)
| ID | RUN_ID |
+----+--------+
| 1 | 1 |
API Data
| ID | DOMAIN_ID | EXPORT_COLUMN | COLUMN_TITLE | VALUE |
+----+-----------+------------------+-------------------+-------+
| 1 | 1 | referringDomains | Referring Domains | 10 |
+----+-----------+------------------+-------------------+-------+
| 2 | 1 | linkCount | Backlink Count | 55 |
Heres my query now:
SELECT a.domain_id, a.export_column, a.column_title, a.value
FROM apidata AS a WHERE domain_id IN
(
SELECT d.id FROM tool_runs AS t
JOIN domains AS d ON d.run_id = t.id
WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
)
ORDER BY a.domain_id
And what I get is:
| DOMAIN_ID | EXPORT_COLUMN | COLUMN_TITLE | VALUE |
+-----------+------------------+-------------------+----------+
| 1 | referringDomains | Referring Domains | 10 |
+-----------+------------------+-------------------+----------+
| 1 | linkCount | Backlink Count | 55 |
But what I want is
| DOMAIN_ID | referringDomains | referringDomains_TITLE | linkCount | linkCount_TITLE |
+-----------+------------------+------------------------+-----------+-----------------+
| 1 | 10 | Referring Domains | 55 | Backlink Count |

Answer 1

What you are trying to is to pivot the table rows into columns. Unfortunately MySQL doesn't have a native pivot table operator, but you can use the CASE expression to do so:
SELECT
a.Domain_id,
MAX(CASE WHEN a.export_column = 'referringDomains' THEN a.value END) AS referringDomains,
MAX(CASE WHEN a.export_column = 'referringDomains' THEN a.column_title END) AS referringDomains_TITLE,
MAX(CASE WHEN a.export_column = 'linkCount' THEN a.value END) AS linkCount,
MAX(CASE WHEN a.export_column = 'linkCount' THEN a.column_title END) AS linkCount_TITLE
FROM apidata AS a
WHERE domain_id IN
(
SELECT d.id FROM tool_runs AS t
JOIN domains AS d ON d.run_id = t.id
WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
)
GROUP BY a.domain_id;
Updated SQL Fiddle Demo
Note that: If you want to do so for all the values in the export_column, you have to write a CASE expression for each value. But you can do that using dynamic sql like this:
SET #ecvalues = NULL;
SET #ectitles = NULL;
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(a.export_column = ''',
a.export_column, ''', a.value , NULL)) AS ', '''', a.export_column , '''')
) INTO #ecvalues
FROM apidata a;
SELECT
GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(a.export_column = ''',
a.export_column, ''', column_title , NULL)) AS ', '''', CONCAT(a.export_column , '_Titles'), '''')
) INTO #ectitles
FROM apidata a;
SET #sql = CONCAT('SELECT
a.Domain_id, ', #ectitles , ',', #ecvalues, '
FROM apidata AS a
WHERE domain_id IN
(
SELECT d.id FROM tool_runs AS t
JOIN domains AS d ON d.run_id = t.id
WHERE id_sha = ''68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A''
)
GROUP BY a.domain_id;');
prepare stmt
FROM #sql;
execute stmt;
You can put that query inside a stored procedure.
Updated SQL Fiddle Demo

Answer 2

Just as a complement to the #MahmoudGamal answer you should know that for any new registry (EXPORT_COLUMN) you will have to add a new case statement.
So in order to do it dynamic you can create a procedure as described on this post at dba.stackexchange.
How to transpose/convert rows as columns in mysql
It shows how to do it dynamically.

Answer 3

If you want columns, go ahead and pivot as the example above. If you only want a single string, for some reporting reason, go ahead and do:
SELECT group_concat(CONCAT_WS(' ',a.domain_id, a.value, a.column_title, a.export_column, 'next row string separator'))
FROM apidata AS a WHERE domain_id IN
(
SELECT d.id FROM tool_runs AS t
JOIN domains AS d ON d.run_id = t.id
WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
)
ORDER BY a.domain_id