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new 26e27b0b47 doc: Document DESCRIBE comman in ddl.md (#16524)
26e27b0b47 is described below
commit 26e27b0b4721dd1cbe790658bb891a1c2be8ceec
Author: K <84141602+krik...@users.noreply.github.com>
AuthorDate: Tue Jun 24 02:18:36 2025 +0530
doc: Document DESCRIBE comman in ddl.md (#16524)
* doc: Document DESCRIBE comman in ddl.md
Add documentation for DESCRIBE and DESC commands with syntax, examples, and
output format explanation.
Fixes #16518
* prettier
---------
Co-authored-by: Andrew Lamb <and...@nerdnetworks.org>
---
docs/source/user-guide/sql/ddl.md | 77 +++++++++++++++++++++++++++++++++++++++
1 file changed, 77 insertions(+)
diff --git a/docs/source/user-guide/sql/ddl.md
b/docs/source/user-guide/sql/ddl.md
index 1d971594ad..f4ed31790d 100644
--- a/docs/source/user-guide/sql/ddl.md
+++ b/docs/source/user-guide/sql/ddl.md
@@ -316,3 +316,80 @@ DROP VIEW [ IF EXISTS ] <b><i>view_name</i></b>;
-- drop users_v view from the customer_a schema
DROP VIEW IF EXISTS customer_a.users_v;
```
+
+## DESCRIBE
+
+Displays the schema of a table, showing column names, data types, and nullable
status. Both `DESCRIBE` and `DESC` are supported as aliases.
+
+<pre>
+{ DESCRIBE | DESC } <b><i>table_name</i></b>
+</pre>
+
+The output contains three columns:
+
+- `column_name`: The name of the column
+- `data_type`: The data type of the column (e.g., Int32, Utf8, Boolean)
+- `is_nullable`: Whether the column can contain null values (YES/NO)
+
+### Example: Basic table description
+
+```sql
+-- Create a table
+CREATE TABLE users AS VALUES (1, 'Alice', true), (2, 'Bob', false);
+
+-- Describe the table structure
+DESCRIBE users;
+```
+
+Output:
+
+```
++--------------+-----------+-------------+
+| column_name | data_type | is_nullable |
++--------------+-----------+-------------+
+| column1 | Int64 | YES |
+| column2 | Utf8 | YES |
+| column3 | Boolean | YES |
++--------------+-----------+-------------+
+```
+
+### Example: Using DESC alias
+
+```sql
+-- DESC is an alias for DESCRIBE
+DESC users;
+```
+
+### Example: Describing external tables
+
+```sql
+-- Create an external table
+CREATE EXTERNAL TABLE taxi
+STORED AS PARQUET
+LOCATION '/mnt/nyctaxi/tripdata.parquet';
+
+-- Describe its schema
+DESCRIBE taxi;
+```
+
+Output might show:
+
+```
++--------------------+-----------------------------+-------------+
+| column_name | data_type | is_nullable |
++--------------------+-----------------------------+-------------+
+| vendor_id | Int32 | YES |
+| pickup_datetime | Timestamp(Nanosecond, None) | NO |
+| passenger_count | Int32 | YES |
+| trip_distance | Float64 | YES |
++--------------------+-----------------------------+-------------+
+```
+
+:::{note}
+The `DESCRIBE` command works with all table types in DataFusion, including:
+
+- Regular tables created with `CREATE TABLE`
+- External tables created with `CREATE EXTERNAL TABLE`
+- Views created with `CREATE VIEW`
+- Tables in different schemas using qualified names (e.g., `DESCRIBE
schema_name.table_name`)
+ :::
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