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Converts a binary string from a specified encoding to the TEXT data type, using the database’s encoding.

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Syntax

CONVERT_FROM
(<bytes>, <src_encoding>)

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Parameters

ParameterDescriptionSupported input types
<bytes>A sequence of bytes representing text in <src_encoding>.BYTEA
<src_encoding>The encoding from which the src <bytes> are derived, which must be constant. The supported source encoding aligns with those supported in the ICU library.TEXT

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Return Type

CONVERT_FROM returns a value of type TEXT.

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Errors

If <src_encoding> is invalid, an error is thrown. If <bytes> are malformed according to <src_encoding>, the behavior is undefined and may result in replacement characters or errors, depending on the encoding. For example, in UTF-8 encoding, malformed bytes are replaced with the � character.

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Examples

Example The following code example uses CONVERT_FROM to convert the binary input \x1212003100 of type BYTEA into a TEXT string using the UTF-16 encoding. All results are displayed in UTF-8 encoding: 
SELECT CONVERT_FROM('\x1212003100'::BYTEA, 'utf16');
Returns The result, ሒ1� consists of:
  • ሒ, the UTF-16 representation of 1212.
  • 1, the UTF-16 representation of 0031.
  • The replacement character �. Because 00 is a single byte, it does not form a valid UTF-16 sequence.
Example The following code example uses CONVERT_FROM to convert the binary input \x31a031ffffffff of type BYTEA into a TEXT string using the windows-1252 encoding: 
SELECT CONVERT_FROM('\x31a031ffffffff'::BYTEA, 'windows-1252');
Returns The result, 1 1ÿÿÿÿ, consists of:
  • 1, the windows-1252 representation of 31.
  •  , the windows-1252 representation of the non-breaking space character a0.
  • ÿ, the windows-1252 representation of ff.
Example The following code example creates a table, which represents an external table, with a BYTEA column that represents text data in a custom encoding that is specified during data loading: 
CREATE TABLE external_bytes_data (a bytea);
INSERT INTO external_bytes_data VALUES ('\x1212003100');
Example The following code example converts the BYTEA column col_bytea into TEXT using the specified encoding UTF-16, and inserts it into text_encoded_data target table: 
CREATE TABLE text_encoded_data (a text);
INSERT INTO text_encoded_data SELECT CONVERT_FROM(a, 'UTF-16') FROM external_bytes_data;
SELECT * FROM text_encoded_data;
In the previous code example, you can replace the UTF-16 input encoding with another encoding supported by the ICU library.
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