Remove element from JSON array for whole table

问题

I have a column filled with JSON arrays. It looks like:

Numbers
'[1,33,5,4,5]'
'[1,2,555,4,5]'
'[1,5,3,4,5]'
'[1,25,3,4,5]'
'[1,2,5,4,5]'
'[1,2,3,4,55]'

I want to remove all instances of 5 (not 55, 555 or 25) so it looks like

Numbers
'[1,33,4]'
'[1,2,555,4]'
'[1,5,3,4]'
'[1,25,3,4]'
'[1,2,4]'
'[1,2,3,4,55]'

I have Full Text Indexing so I can identtify the rows that contain it using CONTAINS(Numbers, '5')

Does anyone know a quick/clean way to remove all the 5's?

I know I could use multiple replace to replace ",5]" "[5," and ",5," but seems like a messy solution.

回答1:

One way to do it without multiple replace is to use openjson and string_agg in a common table expression to get the values needed, and then update the table joined to the cte. Please note that string_agg is supported on 2017 version or higher.

First, create and populate sample table (Please save us this step in your future questions):

DECLARE @T AS TABLE
(
    Numbers varchar(50)
)

INSERT INTO @T(Numbers) VALUES
('[1,33,5,4,5]'),
('[1,2,555,4,5]'),
('[1,5,3,4,5]'),
('[1,25,3,4,5]'),
('[1,2,5,4,5]'),
('[1,2,3,4,55]');

The cte:

WITH CTE AS
(
    SELECT Numbers, '[' + string_agg([Value], ',') +']' As NewNumbers
    FROM @T
    CROSS APPLY
    (SELECT [Value] FROM OPENJSON(Numbers)) As x
    WHERE [Value] != 5
    GROUP BY Numbers
)

The update:

UPDATE T
SET Numbers = NewNumbers
FROM @T As T
JOIN CTE ON T.Numbers = CTE.Numbers

Validate:

SELECT *
FROM @T

Result:

Numbers
[1,33,4]
[1,2,555,4]
[1,3,4]
[1,25,3,4]
[1,2,4]
[1,2,3,4,55]

You can see a demo on DB<>Fiddle.

However, the replace option is much shorter and will work with any version of SQL Server - even as old as 2000 (I think):

UPDATE @T 
SET Numbers = 
    REPLACE(
        REPLACE(
            REPLACE(Numbers, '[5,', '[')
        , ',5]', ']')
    , ',5,', '');

In conclusion, if you are working on 2017 or higher, and need to remove multiple values from an array, the cte + string_agg apporach will probably be easier (since all you have to do is change the where clause in the cte).
For older versions, or for a single value removal, The replace approach might be a better choice.

来源：https://stackoverflow.com/questions/57490929/remove-element-from-json-array-for-whole-table

标签

arrays

json

sql-server

sql-server-2017