Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). 

# SOUNDEX function
<a name="SOUNDEX"></a>

The SOUNDEX function returns the American Soundex value consisting of the first letter of the input string followed by a 3–digit encoding of the sounds that represent the English pronunciation of the string that you specify. For example, `Smith` and `Smyth` have the same Soundex value. 

## Syntax
<a name="SOUNDEX-synopsis"></a>

```
SOUNDEX(string)
```

## Arguments
<a name="SOUNDEX-arguments"></a>

 *string*   
You specify a `CHAR` or `VARCHAR` string that you want to convert to an American Soundex code value. 

## Return type
<a name="SOUNDEX-return-type"></a>

VARCHAR(4)

## Usage notes
<a name="r_SOUNDEX_usage_notes"></a>

The SOUNDEX function converts only English alphabetical lowercase and uppercase ASCII characters, including a–z and A–Z. SOUNDEX ignores other characters. SOUNDEX returns a single Soundex value for a string of multiple words separated by spaces.

```
SELECT SOUNDEX('AWS Amazon');
            
+---------+
| soundex |
+---------+
| A252    |
+---------+
```

SOUNDEX returns an empty string if the input string doesn't contain any English letters.

```
SELECT SOUNDEX('+-*/%');

+---------+
| soundex |
+---------+
|         |
+---------+
```

## Examples
<a name="SOUNDEX-examples"></a>

To return the Soundex value for `Amazon`, use the following example.

```
SELECT SOUNDEX('Amazon');

+---------+
| soundex |
+---------+
| A525    |
+---------+
```

To return the Soundex value for `smith` and `smyth`, use the following example. Note that the Soundex values are the same.

```
SELECT SOUNDEX('smith'), SOUNDEX('smyth');

+-------+-------+
| smith | smyth |
+-------+-------+
| S530  | S530  |
+-------+-------+
```