问题
I have a table with many item_number records which are duplicates within my table and the other columns within the table for each item_number are blank.
All of the records within the table are under product group of g024. However when I run my query it will update all of my items numbers with this.
What I want it to do is for each item_number only populate resource code, operation and operation description only once and not populating the remianing blank fields for each item_number with the criteria within the query.
I will populate these other black fields with a different update query later on.
UPDATE resource1 SET [resource code] ='TOOLASSY', OPERATION = '10', OPERATION_DESCRIPTION = 'MOULD TOOL ASSEMBLY'
WHERE [product group]="G024"
I did try something like this to make the query only update each item_number only once. I looked into the TOP keyword but not sure if it was on the right line or not.
I need something like the DISTINCT keyword within a sub query for an update query.
UPDATE resource1 SET [resource code] ='TOOLASSY', OPERATION = '10', OPERATION_DESCRIPTION = 'MOULD TOOL ASSEMBLY'
WHERE [product group]="G024" AND ITEM_NUMBER IN(SELECT TOP 1 ITEM_NUMBER FROM RESOURCE1)
回答1:
Updated:
UPDATE resource1 SET [resource code] ='TOOLASSY', OPERATION = '10', OPERATION_DESCRIPTION = 'MOULD TOOL ASSEMBLY'
WHERE [product group]="G024" AND [num] IN (SELECT MinNum FROM (SELECT resource1.[product group], resource1.[item_number], MIN(resource1.[num]) AS MinNum FROM resource1 GROUP BY resource1.[product group], resource1.[item_number])
Q1 WHERE Q1.[product group]=resource1.[product group] AND Q1.[item_number]= resource1.[item_number]);
Tested in MSAccess 2010.
来源：https://stackoverflow.com/questions/19999309/updating-records-but-limiting-to-only-one-row-per-duplicate-record