eggroll
Reputation: 1079
SQL Server 2016 "FOR JSON PATH" - Modify JSON nesting
I'm trying to change the nesting of the JSON output from a query using FOR JSON PATH. The FOR JSON AUTO query is almost what I need, but not quite.
Query using FOR JSON AUTO:
SELECT
table_name = tables.name,
table_object_id = tables.object_id,
index_name = indexes.name,
index_id = indexes.index_id,
column_name = columns.name,
column_id = index_columns.index_column_id,
max_length = columns.max_length,
precision = columns.precision,
scale = columns.scale
FROM
sys.indexes indexes
INNER JOIN
sys.index_columns index_columns ON indexes.object_id = index_columns.object_id and indexes.index_id = index_columns.index_id
INNER JOIN
sys.columns columns ON index_columns.object_id = columns.object_id and index_columns.column_id = columns.column_id
INNER JOIN
sys.tables tables ON indexes.object_id = tables.object_id
WHERE tables.name LIKE 'tbl_%'
ORDER BY
tables.name, indexes.index_id, index_columns.index_column_id
FOR JSON AUTO
Query using FOR JSON AUTO Output (snippet):
.
.
.
{
"table_name": "tbl_Agent",
"table_object_id": 176055713,
"indexes": [
{
"index_name": "PK_Task_tbl_Agent",
"index_id": 1,
"columns": [
{
"column_name": "PartitionId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 1
}
]
},
{
"column_name": "AgentId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 2
}
]
}
]
},
{
"index_name": "IX_Task_tbl_Agent_PoolId_AgentName",
"index_id": 2,
"columns": [
{
"column_name": "PartitionId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 1
}
]
},
{
"column_name": "PoolId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 2
}
]
},
{
"column_name": "AgentName",
"max_length": 128,
"precision": 0,
"scale": 0,
"index_columns": [
{
"column_id": 3
}
]
}
]
},
{
"index_name": "IX_Task_tbl_Agent_PoolId_SessionId",
"index_id": 3,
"columns": [
{
"column_name": "PartitionId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 1
}
]
},
{
"column_name": "PoolId",
"max_length": 4,
"precision": 10,
"scale": 0,
"index_columns": [
{
"column_id": 2
}
]
},
{
"column_name": "SessionId",
"max_length": 16,
"precision": 0,
"scale": 0,
"index_columns": [
{
"column_id": 3
}
]
}
]
}
]
},
.
.
.
Each table has all of its indexes nested properly and, within each index, all of the index's columns (these are composite indexes) are nested properly. The only change I want to make is to un-nest index_columns, making column_id part of columns, e.g.:
.
.
.
"columns": [
{
"column_name": "PartitionId",
"max_length": 4,
"precision": 10,
"scale": 0,
---> "column_id": 1
},
{
"column_name": "PoolId",
"max_length": 4,
"precision": 10,
"scale": 0,
---> "column_id": 2
},
{
"column_name": "AgentName",
"max_length": 128,
"precision": 0,
"scale": 0,
---> "column_id": 3
}
]
.
.
.
When I try to use FOR JSON PATH, however, it ends up nesting improperly.
Query using FOR JSON PATH:
SELECT
tables.name AS [tables.table_name],
tables.object_id AS [tables.table_object_id],
indexes.name AS [tables.indexes.index_name],
indexes.index_id AS [tables.indexes.index_id],
columns.name AS [tables.indexes.columns.column_name],
index_columns.index_column_id AS [tables.indexes.columns.column_id],
columns.max_length AS [tables.indexes.columns.max_length],
columns.precision AS [tables.indexes.columns.precision],
columns.scale AS [tables.indexes.columns.scale]
FROM
sys.indexes indexes
INNER JOIN
sys.index_columns index_columns ON indexes.object_id = index_columns.object_id and indexes.index_id = index_columns.index_id
INNER JOIN
sys.columns columns ON index_columns.object_id = columns.object_id and index_columns.column_id = columns.column_id
INNER JOIN
sys.tables tables ON indexes.object_id = tables.object_id
WHERE tables.name LIKE 'tbl_%'
ORDER BY
tables.name, indexes.index_id, index_columns.index_column_id
FOR JSON PATH
Query using FOR JSON PATH Output (snippet):
.
.
.
{
"tables": {
===> "table_name": "tbl_Agent",
"table_object_id": 176055713,
"indexes": {
---> "index_name": "PK_Task_tbl_Agent",
"index_id": 1,
"columns": {
"column_name": "PartitionId",
"column_id": 1,
"max_length": 4,
"precision": 10,
"scale": 0
}
}
}
},
{
"tables": {
===> "table_name": "tbl_Agent",
"table_object_id": 176055713,
"indexes": {
---> "index_name": "PK_Task_tbl_Agent",
"index_id": 1,
"columns": {
"column_name": "AgentId",
"column_id": 2,
"max_length": 4,
"precision": 10,
"scale": 0
}
}
}
},
{
"tables": {
===> "table_name": "tbl_Agent",
"table_object_id": 176055713,
"indexes": {
"index_name": "IX_Task_tbl_Agent_PoolId_AgentName",
"index_id": 2,
"columns": {
"column_name": "PartitionId",
"column_id": 1,
"max_length": 4,
"precision": 10,
"scale": 0
}
}
}
},
.
.
.
While column_id is now where I would like it to be, columns is now the only thing properly nested. Each table is now repeated for each of its indexes, and each index is repeated for each of its columns.
How do I get column_id where I want it (like the output from the FOR JSON PATH query), while maintaining the proper nesting (like the output from the FOR JSON AUTO query)?
UPDATE -- WORKING
Based on DimaSUN's response and Ben's comment, I came up with this query that is now working:
SELECT
tables.name AS [table_name],
tables.object_id AS [table_object_id],
(SELECT
indexes.name AS [index_name],
indexes.index_id AS [index_id],
(SELECT
columns.name AS [column_name],
index_columns.index_column_id AS [column_id],
columns.max_length AS [max_length],
columns.precision AS [precision],
columns.scale AS [scale]
FROM
sys.index_columns index_columns
JOIN
sys.columns columns ON index_columns.object_id = columns.object_id and index_columns.column_id = columns.column_id
WHERE
indexes.object_id = index_columns.object_id and indexes.index_id = index_columns.index_id
ORDER BY
index_columns.index_column_id
FOR JSON PATH
) AS 'columns'
FROM
sys.indexes indexes
WHERE
indexes.object_id = tables.object_id
ORDER BY
indexes.index_id
FOR JSON PATH
) AS 'indexes'
FROM
sys.tables tables
WHERE
tables.name LIKE 'tbl_%'
ORDER BY
tables.name
FOR JSON PATH, ROOT('tables')
New Query Output (snippet):
.
.
.
{
"table_name": "tbl_Agent",
"table_object_id": 176055713,
"indexes": [
{
"index_name": "PK_Task_tbl_Agent",
"index_id": 1,
"columns": [
{
"column_name": "PartitionId",
"column_id": 1,
"max_length": 4,
"precision": 10,
"scale": 0
},
{
"column_name": "AgentId",
"column_id": 2,
"max_length": 4,
"precision": 10,
"scale": 0
}
]
},
{
"index_name": "IX_Task_tbl_Agent_PoolId_AgentName",
"index_id": 2,
"columns": [
{
"column_name": "PartitionId",
"column_id": 1,
"max_length": 4,
"precision": 10,
"scale": 0
},
{
"column_name": "PoolId",
"column_id": 2,
"max_length": 4,
"precision": 10,
"scale": 0
},
{
"column_name": "AgentName",
"column_id": 3,
"max_length": 128,
"precision": 0,
"scale": 0
}
]
},
{
"index_name": "IX_Task_tbl_Agent_PoolId_SessionId",
"index_id": 3,
"columns": [
{
"column_name": "PartitionId",
"column_id": 1,
"max_length": 4,
"precision": 10,
"scale": 0
},
{
"column_name": "PoolId",
"column_id": 2,
"max_length": 4,
"precision": 10,
"scale": 0
},
{
"column_name": "SessionId",
"column_id": 3,
"max_length": 16,
"precision": 0,
"scale": 0
}
]
}
]
},
.
.
.
The AS 'columns' and AS 'indexes' at the ends of the nested selects was a critical piece because otherwise I was getting the following error:
Msg 13605, Level 16, State 1, Line 1
Unnamed tables cannot be used as JSON identifiers as well as unnamed columns cannot be used as key names. Add alias to the unnamed column/table.
Upvotes: 1
Views: 2249
Answers (1)
DimaSUN
Reputation: 921
for XML it looks like
( select
indexes.name AS [index_name],
indexes.index_id AS [index_id],
( select
columns.name AS [column_name],
index_columns.index_column_id AS [column_id],
columns.max_length AS [max_length],
columns.precision AS [precision],
columns.scale AS [scale]
from
sys.index_columns index_columns
JOIN
sys.columns columns ON index_columns.object_id = columns.object_id and index_columns.column_id = columns.column_id
where indexes.object_id = index_columns.object_id and indexes.index_id = index_columns.index_id
FOR xml PATH(''), root('columns'), type
)
from
sys.indexes indexes
where indexes.object_id = tables.object_id
FOR xml PATH(''), root('indices'), type
)
FROM
sys.tables tables
WHERE tables.name LIKE 'tbl_%'
--ORDER BY tables.name, indexes.index_id, index_columns.index_column_id
FOR XML PATH('tables')
replace XML with JSON.
Upvotes: 1
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