motherduck-duckdb-sql

Original：🇺🇸 English

Translated

DuckDB SQL reference for MotherDuck. Use when you need exact DuckDB syntax, function behavior, supported MotherDuck SQL features, or to resolve whether PostgreSQL-oriented SQL will fail on MotherDuck.

2installs

Sourcemotherduckdb/agent-skills

Added on2026-05-11

NPX Install

npx skill4agent add motherduckdb/agent-skills motherduck-duckdb-sql

SKILL.md Content

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DuckDB SQL Reference for MotherDuck

Use this skill when you need exact DuckDB syntax, function behavior, or a quick sanity check that a statement will actually work on MotherDuck.

Source Of Truth

Prefer current DuckDB SQL docs for language features and function semantics.
Use current MotherDuck SQL docs for MotherDuck-only commands such as shares, secrets, snapshots, and Dive operations.
Check MotherDuck version-lifecycle docs for newly released DuckDB features before promising they are available in MotherDuck.
Treat upstream DuckDB 1.5.x docs as ahead of MotherDuck unless the current MotherDuck lifecycle docs confirm the same DuckDB version and feature surface.
Distinguish upstream DuckDB current-version docs from MotherDuck-supported DuckDB versions; MotherDuck can lag upstream current for client compatibility and SQL feature support.
If the connection path matters, verify behavior against the current Postgres-endpoint docs before promising server-mode support.

Default Posture

Write DuckDB SQL, not PostgreSQL SQL, even when the client connects through the Postgres endpoint.
Use fully qualified
```
"database"."schema"."table"
```
names once more than one database or share is in scope.
Prefer DuckDB-native constructs when they simplify the query:
```
GROUP BY ALL
```
,
```
QUALIFY
```
,
```
UNION BY NAME
```
,
```
arg_max
```
,
```
EXCLUDE
```
, and
```
REPLACE
```
.
When porting SQL from another engine, translate functions, date arithmetic, identifier quoting, and type casts explicitly instead of assuming compatibility.
For upstream DuckDB 1.5 features such as
```
VARIANT
```
, native
```
GEOMETRY
```
,
```
date_trunc
```
return-type changes, ODBC scanner behavior, or lakehouse-format changes, verify current MotherDuck support before adding them to production guidance.
Check whether the statement depends on local files, extension install/load, temporary-table behavior, or other client-only features before claiming it will work in MotherDuck.
Treat snapshot, restore, and
```
UNDROP DATABASE
```
statements as operational SQL with plan-specific retention behavior, not ordinary analytical syntax.
Treat MotherDuck SQL as an additional surface on top of DuckDB SQL, not a replacement for it.

Workflow

Confirm the connection path and whether the question is about syntax, feature support, or a specific error.
Write or repair the statement in DuckDB SQL first.
Verify any MotherDuck-only command or server-mode limitation against the current docs.
If the user needs exact syntax or function details, open
```
references/SYNTAX_REFERENCE.md
```
.

Open Next

```
references/SYNTAX_REFERENCE.md
```
for DuckDB data types, friendly SQL features, functions, complex types, and common MotherDuck-specific gotchas

Related Skills

```
motherduck-query
```
for writing and validating analytical SQL against live MotherDuck data
```
motherduck-connect
```
when syntax support depends on PG endpoint versus native DuckDB behavior
```
motherduck-explore
```
when the problem is really missing schema context rather than missing syntax knowledge