Query Syntax - Update

This query returns the proper values...

                SELECT j.JOB_ID, MAX(l.DATE_WORK) AS LAST_DAY_WORKED
                FROM job j
                INNER JOIN labor l ON j.JOB_ID = l.JOB_ID
                WHERE j.JSTATUS = 'I'
                AND j.DELETED = 'N'
                AND l.DELETED = 'N'
                GROUP BY j.JOB_ID
                ORDER BY LAST_DAY_WORKED;

When I run this update it doesn't update the LAST_WORK field.

    UPDATE job AS target
    INNER JOIN (
                SELECT j.JOB_ID, MAX(l.DATE_WORK) AS LAST_DAY_WORKED
                FROM job j
                INNER JOIN labor l ON j.JOB_ID = l.JOB_ID
                WHERE j.JSTATUS = 'I'
                AND j.DELETED = 'N'
                AND l.DELETED = 'N'
                GROUP BY j.JOB_ID
               ) AS source
                 ON target.JOB_ID = source.JOB_ID
    SET target.LAST_WORK = source.LAST_DAY_WORKED;
hdcowboyazAsked:
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chaauCommented:
It is a limitation of MySQL. Please check the official manual here (closer to the end):
Currently, you cannot update a table and select from the same table in a subquery.
You need to use a different syntax:
    UPDATE job AS target
    SET target.LAST_WORK =  (
                SELECT MAX(l.DATE_WORK) AS LAST_DAY_WORKED
                FROM job j
                INNER JOIN labor l ON j.JOB_ID = l.JOB_ID
                WHERE j.JOB_ID = target.JOB_ID
                AND j.JSTATUS = 'I'
                AND j.DELETED = 'N'
                AND l.DELETED = 'N'
               );

Open in new window

0
hdcowboyazAuthor Commented:
So how can this be done?
0
chaauCommented:
Have you checked my syntax? Doesn't it work? What error are you getting?
0
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hdcowboyazAuthor Commented:
Make a another job table with only JOB_ID and LAST_WORK?
0
chaauCommented:
Try this one:
UPDATE job AS target
    SET target.LAST_WORK =  (
                SELECT MAX(l.DATE_WORK) AS LAST_DAY_WORKED
                FROM labor l 
                WHERE l.JOB_ID = target.JOB_ID
               )
WHERE target.JSTATUS = 'I'
                AND target.DELETED = 'N'
                AND target.DELETED = 'N';

Open in new window

0
hdcowboyazAuthor Commented:
Sorry I didn't fully read your first response. The first query you sent returned this error.

<e>Query: UPDATE job AS target SET target.LAST_WORK = ( SELECT MAX(l.DATE_WORK) AS LAST_DAY_WORKED FROM job j INNER JOIN labor l ON j.JOB_...

Error Code: 1093
You can't specify target table 'target' for update in FROM clause

The second query returned this error.

<e>Query: UPDATE job AS target SET target.LAST_WORK = ( SELECT MAX(l.DATE_WORK) AS LAST_DAY_WORKED FROM labor l WHERE l.JOB_ID = target.JO...

Error Code: 1048
Column 'LAST_WORK' cannot be null
0
hdcowboyazAuthor Commented:
If it helps

                AND j.DELETED = 'N'
                AND l.DELETED = 'N'

can be removed from the query.
0
PortletPaulfreelancerCommented:
Error Code: 1048
Column 'LAST_WORK' cannot be null


Then that field has a NOT NULL condition applied to it but the inner subquery is returning NULLs (not sure why because I don't know your data).

So, try ensuring the inner subquery does not return NULLs

Please read this bit carefully! You will have to apply your own knowledge to this. I'm guessing

UPDATE job AS target
    SET target.LAST_WORK =  (
                SELECT MAX(l.DATE_WORK) AS LAST_DAY_WORKED
                FROM labor l 
                WHERE l.JOB_ID = target.JOB_ID
                AND l.DATE_WORK IS NOT NULL /* you need to consider this bit: find conditions that stop NULLs being returned */
               )
WHERE target.JSTATUS = 'I'
                AND target.DELETED = 'N' /* remove if you want to, your choice */
                AND target.DELETED = 'N' /* remove if you want to, your choice */
;

Open in new window

Because this is a complete guess I would prefer it if you didn't just report the next error, but gave such errors some thought. In many cases they aren't that hard to interpret.
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hdcowboyazAuthor Commented:
No errors, however the original query returned 170 values and your last query returned 229.
I checked three Jobs and the dates where the same in both queries.
For some reason it updated more rows, which may not be an issue.

I will check more in the morning

Thanks
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PortletPaulfreelancerCommented:
OK. No errors is good.
Increase of records is counter-intuitive. perhaps by removing:
               AND j.DELETED = 'N'
                AND l.DELETED = 'N'

& I do hope you are doing this in a test environment.
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hdcowboyazAuthor Commented:
I left those two in, so results should be the same.  It is in a test environ
0
hdcowboyazAuthor Commented:
All good now
0
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Query Syntax

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