How to I prevent repetitive columns in FOR JSON PATH SQL queries? - json

Question

So, I'm trying to get data from MSSQL to update some fields in an HTML form, which includes 1 checkbox and a set of options for a select input.
I thought I was being smart by writing my query as shown below. It gets BOTH the two fields at once, instead of two independent queries... I mean, it's OKAY, but I have a lot of repeated items.
Is there a way to flatten this out?
// how do I flatten this
{
"Calculated": [
{
"Calculated": false
}
],
"Schedule": [
{
"Schedule": "THX-1138"
},
{
"Schedule": "LUH-3417"
},
{
"Schedule": "SEN-5241"
}
]
}
// into something more like this?
{
"Calculated": false,
"Schedule": [
"THX-1138",
"LUH-3417",
"SEN-5241"
]
}
here is the query:
declare
#EffectDate smalldatetime = '07-01-2012'
,#Grade varchar(3) = '001'
,#Schedule varchar(9) = 'THX-1138'
,#Step smallint = '15'
,#jsonResponse nvarchar(max)
;
select #jsonResponse = (
select
[Calculated] =
(
select
b.Calculated
from
tblScalesHourly a
inner join
tblSchedules b
on a.EffectDate = b.EffectDate
and a.Schedule = b.Schedule
where
a.EffectDate = #EffectDate
and a.Schedule = #Schedule
and a.Grade = #Grade
and a.Step = #Step
for json path
)
,[Schedule] =
(
select
Schedule
from
tblSchedules
where
EffectDate = #EffectDate
and Calculated = 0
order by
Schedule asc
for json path
)
for json path, without_array_wrapper
)

Answer 1

It's probably a late answer, but I'm able to reproduce this issue with the following test data:
declare #jsonResponse nvarchar(max)
select #jsonResponse = (
select
[Calculated] =
(
select CONVERT(bit, 0) AS Calculated
for json path
)
,
[Schedule] =
(
select Schedule
from (values ('THX-1138'), ('LUH-3417'), ('SEN-5241')) tblSchedules (Schedule)
order by Schedule asc
for json path
)
for json path, without_array_wrapper
)
You can get the expected results with the following approach. Note, that you can't generate a JSON array of scalar values using FOR JSON, so you need to use a string aggregation (FOR XML PATH('') for SQL Server 2016 or STRING_AGG() for SQL Server 2017+):
select #jsonResponse = (
select
[Calculated] = (
select CONVERT(bit, 0) AS Calculated
)
,
[Schedule] = JSON_QUERY(CONCAT(
'["',
STUFF(
(
select CONCAT('","', Schedule)
from (values ('THX-1138'), ('LUH-3417'), ('SEN-5241')) tblSchedules (Schedule)
order by Schedule asc
for xml path('')
), 1, 3, ''
),
'"]'
))
for json path, without_array_wrapper
)
Output:
{"Calculated":false,"Schedule":["LUH-3417","SEN-5241","THX-1138"]}
And finally, using the statement from the question (not tested):
declare
#EffectDate smalldatetime = '07-01-2012'
,#Grade varchar(3) = '001'
,#Schedule varchar(9) = 'THX-1138'
,#Step smallint = '15'
,#jsonResponse nvarchar(max)
;
select #jsonResponse = (
select
[Calculated] = (
select
b.Calculated
from
tblScalesHourly a
inner join
tblSchedules b
on a.EffectDate = b.EffectDate
and a.Schedule = b.Schedule
where
a.EffectDate = #EffectDate
and a.Schedule = #Schedule
and a.Grade = #Grade
and a.Step = #Step
),
[Schedule] = JSON_QUERY(CONCAT(
'["',
STUFF(
(
select CONCAT('","', Schedule)
from
tblSchedules
where
EffectDate = #EffectDate
and Calculated = 0
for xml path('')
), 1, 3, ''
),
'"]'
))
for json path, without_array_wrapper
)