Dv Query Agent Skill

Skill: Query — Read and Analyze Dataverse Records

> This skill uses Python exclusively. Do not use Node.js, JavaScript, or any other language for Dataverse scripting. See the overview skill's Hard Rules.

Reads: prefer a managed surface, choose by shape

Pick MCP or the SDK by the shape of the read — both handle auth, paging, and retry (see the routing table below and the overview's Tool Capabilities / Hard Rule 2). MCP fits small, interactive reads; the SDK fits bulk iteration and analytics. For $apply aggregation and N:N $expand, prefer client.query.fetchxml() (aggregates + link-entity) or the managed dataverse api escape hatch; reach for hand-rolled urllib/get_token() only to stay in-process inside a tight Python loop (e.g. paging thousands of rows with client-side processing — see web-api-advanced.md).

Dataverse CLI gotchas (custom tables + Windows)

When you drive the dataverse CLI directly (headless reads/CRUD), two empirical traps:

• Custom-table SQL pluralization. dataverse data query in SQL mode auto-pluralizes the table name, and irregular plurals resolve wrong: FROM im_category looks up entity set im_categorys and returns a 404 that reads like "table missing." It is not — switch to OData mode with the explicit entity set: dataverse data query --table im_categories --select im_name. Discover the real EntitySetName from EntityDefinitions when unsure; never conclude the table doesn't exist from this 404.
• Windows shell quoting. Wrap the whole --path value in double quotes so cmd.exe/PowerShell don't treat & as a command separator. Keep & literal — it separates OData query options; encoding it to %26 merges them and breaks the query. Encode only $->%24 (in PowerShell a bare $select is read as a variable). If an unquoted & splits the command, the wrapper can exit nonzero *even when the API returned valid JSON* — quoting prevents it. (This is why the dataverse api request examples in other skills quote the path, use %24, and leave & literal.)

ERP target is a separate path. ERP (Finance and Operations), when linked to a Dataverse env, does not go through the Python SDK. See references/erp-reads.md.

How to Answer Data Questions

When the user asks a question about their data, pick the approach by what they're asking, not by which API you know:

| User asks... | Approach | Why |

|---|---|---|

| "show me open tickets" / simple filter | MCP read_query (if available) or client.records.list(table, filter=...) | Small result, no aggregation |

| "how many X" / simple count | MCP read_query, or client.query.sql("SELECT COUNT(*) AS n FROM <table> WHERE ...") | Server-side count (no row download) |

| Single-table aggregation (most/sum/avg/top-N) | $apply (raw) or client.query.sql() GROUP BY | Both run server-side, return only grouped results |

| Cross-table aggregation | client.query.sql("...INNER JOIN...GROUP BY...") or client.query.fetchxml(...) (server-side); else builder->DataFrame + pd.merge() | sql() supports INNER/LEFT JOIN + GROUP BY; pandas merge for shapes SQL can't express |

| "show me X with related Y" / resolve lookups | client.records.list(table, expand=...) or QueryBuilder | Lookup resolution |

| "export this data" / bulk extract | client.query.builder(t).select(...).execute().to_dataframe() | Direct to DataFrame → CSV |

| "load into notebook" / interactive analysis | client.query.builder(t).select(...).execute().to_dataframe() | pandas native |

| "find duplicates" / complex filter | client.records.list(table, filter=...) or QueryBuilder | SDK handles pagination |

| Simple filtered read (<5K rows) | client.query.sql() | Lightweight SQL SELECT with WHERE, ORDER BY, TOP |

Key principle: Let the server do the work. For single-table aggregation, use $apply (raw) or client.query.sql() GROUP BY — both run server-side and return only grouped results. For cross-table questions, prefer a server-side sql() JOIN (INNER/LEFT) or fetchxml() link-entity; when SQL can't express it, pull each table via client.query.builder(t).select(...).execute().to_dataframe() and pd.merge() — the merge is sub-second; the bottleneck is network transfer, which select minimizes.

Always query the live Dataverse environment. Do not query local copies, cached files, or source databases when the user expects results from Dataverse. The data in Dataverse is the source of truth.

SQL Queries — client.query.sql()

client.query.sql() uses the Dataverse Web API ?sql= parameter — a T-SQL subset. It supports SELECT / SELECT DISTINCT / SELECT TOP N (0-5000), INNER JOIN / LEFT JOIN, WHERE, GROUP BY, ORDER BY, OFFSET/FETCH, and COUNT/SUM/AVG/MIN/MAX. It does NOT support SELECT *, subqueries, CTEs, HAVING, UNION, RIGHT/FULL/CROSS JOIN, CASE, or string/date/math functions. Results are capped at ~5,000 rows.

When to use: Fast filtered reads on tables with <5K rows. For these, it's significantly faster (~2-6s) than page iteration or DataFrames because it's a single HTTP call.

# Fast filtered read on small tables (<5K rows)
results = client.query.sql(
    "SELECT TOP 100 name, estimatedvalue "
    "FROM opportunity "
    "WHERE statecode = 0 "
    "ORDER BY estimatedvalue DESC"
)
for r in results:
    print(f"{r['name']}: ${r.get('estimatedvalue', 0):,.0f}")

Do NOT use for: Tables >5K rows (results silently truncated), SELECT *, subqueries/CTEs, HAVING, UNION, RIGHT/FULL/CROSS JOIN, or functions. INNER/LEFT JOIN and GROUP BY are supported — use them for server-side joins/aggregation on <5K-row results; for larger or unsupported shapes use fetchxml() or $apply.

FetchXML — server-side joins and aggregates

For SQL-JOIN scenarios or aggregates the OData builder cannot express, use FetchXML. client.query.fetchxml(xml) returns an inert query object — no HTTP is made until you call .execute() (eager, all pages) or .execute_pages() (lazy, one page at a time). Both return QueryResult pages with .to_dataframe().

query = client.query.fetchxml("""
  <fetch top="50">
    <entity name="account">
      <attribute name="name" />
      <link-entity name="contact" from="parentcustomerid" to="accountid" alias="c" link-type="inner">
        <attribute name="fullname" />
      </link-entity>
    </entity>
  </fetch>
""")

result = query.execute()          # collect all pages
df = result.to_dataframe()

# Or stream one page at a time for large results:
for page in query.execute_pages():
    print(page.to_dataframe().shape)

Discover queryable columns — client.query.sql_columns()

Before writing a SQL or $select read, list the columns the SQL endpoint can actually query — virtual and computed lookup-display columns are excluded. Each entry has name, type, is_pk, is_name, and label.

for c in client.query.sql_columns("account"):
    print(f"{c['name']:30s} {c['type']:20s} PK={c['is_pk']}")

For deeper schema inspection — full column metadata and table relationships — use dv-metadata

(client.tables.list_columns(), client.tables.list_relationships(),

client.tables.list_table_relationships()).

Skill boundaries

| Need | Use instead |

|---|---|

| Create, update, delete records (Dataverse) | dv-data |

| Query, create, update, delete records (ERP) | See references/erp-reads.md and erp-writes |

| Create tables, columns, relationships | dv-metadata |

| Export or deploy solutions | dv-solution |

Setup

import os, sys
sys.path.insert(0, os.path.join(os.getcwd(), "scripts"))
from auth import get_client

# get_client sets a plugin attribution context on the User-Agent header.
# Do not modify the context value — it is a closed schema for server-side
# telemetry (app/skill/agent). Never include secrets or PII.
client = get_client("dv-query")

get_client(skill) handles auth, environment URL, and plugin attribution (User-Agent tagging). See scripts/auth.py. For scripts that run to completion, wrap the returned client in a with statement for automatic connection cleanup. For ERP, use ERP MCP or the Dataverse CLI --target erp path — see references/erp-reads.md.

Field Name Casing Rule

Getting this wrong causes 400 errors.

| Property type | Convention | Example | When used |

|---|---|---|---|

| Structural (columns) | LogicalName — always lowercase | new_name, new_priority | $select, $filter, $orderby |

| Navigation (lookups) | Navigation Property Name — case-sensitive, matches $metadata | new_AccountId | $expand |

• System table navigation properties (e.g., parentaccountid, ownerid): lowercase
• Custom lookup navigation properties: case-sensitive, match $metadata SchemaName (e.g., new_AccountId)

Query Records

client.records.list() is the primary read method on the GA SDK. It collects all pages and returns a flat QueryResult you iterate directly (records, not pages). For very large result sets, client.records.list_pages() streams one QueryResult per HTTP page. Always use select= to limit columns.

# list() -- flat QueryResult, iterate records directly
result = client.records.list(
    "new_ticket",
    select=["new_name", "new_priority", "new_status"],
    filter="new_status eq 100000000",
    orderby=["new_name asc"],
    top=50,
)
for r in result:
    print(r["new_name"], r["new_priority"])

print(f"{len(result)} tickets")   # QueryResult supports len(), indexing, .first(), .to_dataframe()

For large tables where you do not want every row in memory at once, stream pages:

for page in client.records.list_pages("new_ticket", select=["new_name"], page_size=200):
    for r in page:          # each page is a QueryResult
        print(r["new_name"])

Each record is a Record object that supports dict-like access: r["column"], r.get("column"), r.keys(). Do not use r.data.get() -- use r.get() directly.

> Migrating from records.get(): records.get() is deprecated on the GA SDK. Replace for page in client.records.get(...): for r in page: with for r in client.records.list(...): (flat), or keep the page loop using list_pages(...). Replace a by-GUID records.get(table, guid) with records.retrieve(table, guid) (returns None if not found).

Fetch a Single Record by ID

client.records.retrieve() returns the record, or None if no row has that GUID (no exception on 404).

record = client.records.retrieve("new_ticket", "<record-guid>",
    select=["new_name", "new_priority", "new_status"])
if record is not None:
    print(record["new_name"])
else:
    print("Ticket not found")

$select with Lookup Columns (GUID-free display)

To show display names instead of GUIDs, request the formatted value annotation via include_annotations:

for r in client.records.list("opportunity",
    select=["name", "estimatedvalue", "_parentaccountid_value"],
    include_annotations="OData.Community.Display.V1.FormattedValue",
):
    account_name = r.get("[email protected]")
    print(f"{r['name']} — {account_name}")

You MUST pass include_annotations — without it, the Prefer: odata.include-annotations header is not sent and formatted values are not in the response. Use "*" for all annotations or the specific annotation name above.

Formatted values are available for lookup, choice, status, and owner fields.

$expand — Resolve Lookup to Full Related Record

for r in client.records.list("opportunity",
    select=["name", "estimatedvalue"],
    expand=["parentaccountid($select=name)"],   # nested $select avoids fetching all account columns
):
    account = r.get("parentaccountid") or {}
    print(f"{r['name']} — {account.get('name', 'Unknown')}")

Always use nested $select inside $expand — without it, Dataverse returns every column on the related entity, which wastes bandwidth and memory.

$expand with multiple custom lookups

for r in client.records.list(
    "new_ticket",
    select=["new_name", "new_priority", "new_status"],
    expand=["new_CustomerId($select=new_name)", "new_AgentId($select=new_name)"],  # nested $select + case-sensitive nav props
):
    customer = r.get("new_CustomerId") or {}
    agent    = r.get("new_AgentId") or {}
    print(f"{r['new_name']} | {customer.get('new_name','')} | {agent.get('new_name','')}")

> expand uses the Navigation Property Name (new_CustomerId), not the lowercase logical name (new_customerid). Using lowercase causes a 400 error.

Advanced query patterns (raw Web API)

$apply aggregation and N:N $expand on the OData path are raw-only. Note the SDK does cover most aggregation/joins — client.query.sql() (INNER/LEFT JOIN, GROUP BY, COUNT/SUM/AVG) and client.query.fetchxml() (aggregate + link-entity). Reach for raw Web API only for the $apply transform and N:N $expand. See references/web-api-advanced.md for full code samples.

Quick reference:

• $expand on N:N relationships: GET /<entitySet>?$expand=<n:n_nav>($select=...) — single page only; follow @odata.nextLink for >5,000 results.
• $apply for aggregations: runs server-side, returns grouped results in one call. Patterns: groupby((col),aggregate(metric with sum as total)), aggregate($count as count), aggregate(amount with average as avg). 50K source-record limit.
• Cross-table aggregation: $apply only works within one entity set. Prefer client.query.sql() (INNER/LEFT JOIN + GROUP BY) or fetchxml() link-entity; else pull each table via client.query.builder(t).select(...).execute().to_dataframe() → pd.merge() → groupby(). Always pass select; without it transfers 10-20x more data.

QueryBuilder — Fluent Query API

Chainable builder for complex queries that would be awkward as a single OData URL or FetchXML string. Full reference and examples in references/querybuilder.md.

Jupyter Notebook Setup

For interactive querying in notebooks (auth + DataverseClient + DataFrame display), see references/jupyter-setup.md.

Querying ERP data

On ERP-linked envs, ERP reads do not go through DataverseClient. Use ERP MCP or dataverse data query/get/count --target erp. See references/erp-reads.md.

Common Query Errors

| Status | Cause | Fix |

|---|---|---|

| 400 | Wrong field casing in $select/$filter (must be lowercase LogicalName) or $expand (must be case-sensitive Navigation Property Name) | Verify names via EntityDefinitions(LogicalName='...')/Attributes |

| 400 | Unsupported SQL — MCP read_query rejects DISTINCT/HAVING/subqueries/OFFSET/UNION/CAST/CONVERT/CASE/date-functions (but allows JOIN + GROUP BY); client.query.sql() rejects SELECT */subqueries/CTE/HAVING/UNION/RIGHT/FULL/CROSS JOIN/functions (but allows INNER/LEFT JOIN, GROUP BY, DISTINCT) | Use fetchxml()/$apply for shapes sql() can't express, or pandas for cross-table |

| 404 | Table logical name not found | Check spelling — use client.tables.get("<name>") to verify |

| 429 | Rate limited | SDK retries automatically; reduce page size or add delays between pages |

For HttpError handling in SDK scripts, see the error handling pattern in dv-data.

Windows Scripting Notes

• ASCII only in .py files — curly quotes and em dashes cause SyntaxError on Windows.
• No python -c for multiline code — write a .py file instead.
• Generate GUIDs in scripts: str(uuid.uuid4()), not shell backtick substitution.