# DESCRIBE and SHOW Statements
source: https://docs.chalk.ai/docs/chalksql/statements/describe

## Inspect the schema of a table or query, or list available tables.

The DESCRIBE statement returns the schema of a table or of an arbitrary
query. SHOW <table> is a synonym for DESCRIBE <table>, and SHOW TABLES
lists the tables available in the Chalk catalog.

### Examples

```
-- Describe a data source table
DESCRIBE "my_postgres.public.users";

-- Describe the output schema of a query without running it over all data
DESCRIBE SELECT user_id, sum(amount) AS total
FROM "my_bigquery.my_dataset.transactions"
GROUP BY user_id;

-- List all available tables
SHOW TABLES;
```

### DESCRIBE

```
DESCRIBE "catalog.schema.table";
DESCRIBE select_statement;
SHOW "catalog.schema.table";
```

DESCRIBE returns one row per column with the following schema, mirroring
DuckDB's DESCRIBE output:

| Column        | Type   | Description                                     |
| ------------- | ------ | ----------------------------------------------- |
| `column_name` | string | The name of the column                          |
| `column_type` | string | The data type of the column                     |
| `null`        | string | `YES` if the column is nullable, `NO` otherwise |
| `key`         | string | Always `NULL`                                   |
| `default`     | string | Always `NULL`                                   |
| `extra`       | string | Always `NULL`                                   |

DESCRIBE is compiled as a table expression, so it can also be used in the
FROM clause of a SELECT:

```
SELECT column_name
FROM (DESCRIBE "my_postgres.public.users")
WHERE column_type = 'string';
```

### SHOW TABLES

```
SHOW TABLES;
```

Lists the tables visible to Chalk SQL. It is equivalent to querying the
tables view of the information_schema schema:

```
SELECT * FROM chalk.information_schema.tables;
```

To explore available catalogs and schemas interactively, you can also use the
Database Explorer in the
dashboard, or query chalk.information_schema.schemas.

### Limitations

- SHOW DATABASES is not supported.
- SUMMARIZE is not supported.