Returns the Soundex code for a string. Soundex is a phonetic algorithm that indexes names by sound, as pronounced in English. The algorithm produces a four-character code consisting of a letter followed by three digits.

Non-alphabetic characters are ignored when generating the Soundex code. If the input string contains no alphabetic characters, SOUNDEX returns an empty string.

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Syntax

SOUNDEX(<expression>)

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Parameters

ParameterDescriptionSupported input types
<expression>The string for which to generate the Soundex code.TEXT

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Return Type

TEXT

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Example

The following example generates Soundex codes for different variations of a name:

SELECT
    SOUNDEX('Smith') as soundex_smith,
    SOUNDEX('Smyth') as soundex_smyth,
    SOUNDEX('SMITH') as soundex_upper

Returns: S530, S530, S530

The following example shows the behavior with strings containing no alphabetic characters:

SELECT
    SOUNDEX('123') as soundex_numbers,
    SOUNDEX('!@#$') as soundex_symbols,
    SOUNDEX('') as soundex_empty

Returns: , , “