MySQL UPDATE with SUBQUERY of the same table

Question

I work with a complex MySQL database that collects form data. I simplified the layout in the test example table below:

|FormID|FieldName|  FieldValue |
|   1  |   city  |   Houston   |
|   1  | country |     USA     |
|   2  |   city  |   New York  |
|   2  | country |United States|
|   3  | property|   Bellagio  |
|   3  |  price  |     120     |
|   4  |   city  |   New York  |
|   4  |zip code |    12345    |
|   5  |   city  |   Houston   |
|   5  | country |     US      |

Via phpMyAdmin I need to make global updates for some tables, in particular, I want to update all FieldValue entries in the "United States of America" ​​using the FieldName "country" that have the same FormID as the FieldName "city" and FieldValue "Houston".

I can easily display these records using the SELECT statement, either using SUBQUERY or using INNER JOIN:

SELECT FieldValue
FROM test
WHERE FormID
IN (
   SELECT FormID
   FROM test
   WHERE FieldName =  "city"
   AND FieldValue =  "Houston"
   )
AND FieldName =  "country"

Or:

SELECT a.FieldValue
FROM test a
INNER JOIN test b ON a.FormID = b.FormID
WHERE a.FieldName = "country"
AND b.FieldName = "city"
AND b.FieldValue = "Houston"

UPDATE. MySQL, , join union. , . - , ?

Answer 1

, , . :

:

UPDATE mytable p1 SET p1.type= 'OFFER' WHERE p1.parent IN 
    (SELECT p2.id from mytable p2 WHERE p2.actu_id IS NOT NULL);

:

UPDATE mytable p1 SET p1.type= 'OFFER' WHERE p1.parent IN 
    (SELECT p2.id from (SELECT * FROM mytable) p2 WHERE p2.actu_id IS NOT NULL);

" (SELECT * FROM mytable) p2" ,

Answer 2

, :

UPDATE test AS a
JOIN test AS b ON a.id = b.id
    SET a.name = 'New Name'
WHERE a.id = 104;

? : MySQL v5.6.

Answer 3

Hoyle's solution, ANSI-SQL will:

Update test
Set name = "United States of America"
Where FormId In (
                Select T1.FormID
                From test As T1
                Where T1.FieldName = 'city'
                    And T1.FieldValue = 'Houston'
                )
    And FieldName = 'country'

I think you are missing that you need to use an alias in a table in a subquery.