# Table and column capitalization

When working with CARTO, how your table and column names are handled depends on two factors: your data warehouse provider and how you access the data.

## How you access data matters

| Access method                                                      | How identifiers are handled                                                      |
| ------------------------------------------------------------------ | -------------------------------------------------------------------------------- |
| **Table sources** (Data Explorer, Builder table source, Workflows) | CARTO handles quoting automatically, but has limitations with non-standard names |
| **SQL Query sources** (Builder SQL editor)                         | You control quoting — full flexibility but requires knowledge of provider rules  |

## Provider-specific rules

Each data warehouse treats unquoted identifiers differently:

| Provider       | Default behavior           | Quote character     |
| -------------- | -------------------------- | ------------------- |
| **BigQuery**   | Case-sensitive (unchanged) | `` ` `` (backticks) |
| **Snowflake**  | Converted to UPPERCASE     | `"` (double quotes) |
| **PostgreSQL** | Converted to lowercase     | `"` (double quotes) |
| **Redshift**   | Converted to lowercase     | `"` (double quotes) |
| **Databricks** | Case-insensitive           | `` ` `` (backticks) |
| **Oracle**     | Converted to UPPERCASE     | `"` (double quotes) |

## Known limitations with table sources

When loading **tables** in Data Explorer, Builder (table source), or Workflows, certain column naming patterns are not fully supported.

### **Unsupported patterns**

| Provider          | Unsupported pattern                          | Example                   | Workaround                                           |
| ----------------- | -------------------------------------------- | ------------------------- | ---------------------------------------------------- |
| **Snowflake**     | Lowercase column names (created with quotes) | `"myColumn"`, `"revenue"` | Use SQL Query source, or rename columns to UPPERCASE |
| **Oracle**        | Lowercase column names (created with quotes) | `"myColumn"`, `"revenue"` | Use SQL Query source, or rename columns to UPPERCASE |
| **PostgreSQL**    | Uppercase column names (created with quotes) | `"MyColumn"`, `"Revenue"` | Use SQL Query source, or rename columns to lowercase |
| **All providers** | Columns with special characters              | `my-column`, `my column`  | Use SQL Query source, or rename columns              |
| **All providers** | SQL reserved words as column names           | `select`, `from`, `where` | Use SQL Query source, or rename columns              |

{% hint style="warning" %}
**Why this happens:** When you create a column with quotes in your warehouse (e.g., `"myColumn"` in Snowflake), the warehouse preserves that exact casing. However, when CARTO builds queries for table sources, it may not apply the required quoting for these edge cases.
{% endhint %}

## Using SQL Query sources

SQL Query sources give you full control over identifier quoting. Use the appropriate quote character for your warehouse:

### Snowflake

Double quotes preserve lowercase or mixed case:

```sql
SELECT "myColumn", "Revenue_2024" FROM "MySchema"."SalesData"
```

### PostgreSQL and Redshift

Double quotes preserve uppercase or mixed case:

```sql
SELECT "MyColumn", "Revenue_2024" FROM "public"."SalesData"
```

### BigQuery

Backticks for all identifiers; case is always preserved:

```sql
SELECT myColumn, Revenue_2024 FROM `project.dataset.SalesData`
```

### Databricks

Backticks for special characters; case doesn't matter:

```sql
SELECT myColumn FROM `my-catalog`.schema.sales_data
```

### Oracle

Double quotes preserve lowercase or mixed case:

```sql
SELECT "myColumn", "Revenue_2024" FROM SCHEMA_NAME."SalesData"
```

## Best practices

To ensure compatibility across all CARTO features, use naming conventions that match your provider's default behavior:

{% hint style="info" %}
**Recommended naming conventions**
{% endhint %}

| Provider                  | Recommended naming                    |
| ------------------------- | ------------------------------------- |
| **Snowflake**             | `UPPERCASE` or `UPPER_SNAKE_CASE`     |
| **PostgreSQL / Redshift** | `lowercase` or `snake_case`           |
| **BigQuery**              | Any consistent style (case-sensitive) |
| **Databricks**            | Any style (`snake_case` recommended)  |
| **Oracle**                | `UPPERCASE` or `UPPER_SNAKE_CASE`     |

**General guidelines:**

* Use `snake_case` with letters matching your provider's default (uppercase for Snowflake and Oracle, lowercase for PostgreSQL)
* Avoid spaces, hyphens, and special characters in names
* Avoid SQL reserved words (`select`, `from`, `where`, `order`, `group`, etc.)
* If you must use non-standard names, access the data via SQL Query source

## Troubleshooting

| Error                                                 | Likely cause                                          | Solution                                               |
| ----------------------------------------------------- | ----------------------------------------------------- | ------------------------------------------------------ |
| "Column not found" in Snowflake                       | Column was created with lowercase (quoted)            | Use SQL Query source with proper quoting: `"myColumn"` |
| "Column does not exist" in PostgreSQL                 | Column was created with uppercase (quoted)            | Use SQL Query source with proper quoting: `"MyColumn"` |
| "ORA-00904: invalid identifier" in Oracle             | Column was created with lowercase (quoted)            | Use SQL Query source with proper quoting: `"myColumn"` |
| Table loads but some columns missing                  | Column names use reserved words or special characters | Use SQL Query source                                   |
| Works in warehouse console, fails in CARTO table view | Non-standard identifier naming                        | Use SQL Query source instead                           |


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