Important

The SingleStore 9.1 release candidate (RC) is available now. It will be promoted to general availability (GA) soon and at that time it will be renamed to SingleStore 10.

In the interim, SingleStore 9.1 RC can be used to preview, evaluate, and provide feedback on the new and upcoming features in SingleStore 10, while SingleStore 9.0 is recommended for production workloads.

BSON_EXTRACT_STRING

Syntax

BSON_EXTRACT_STRING(<input> [, path_key_1, path_key_2,.., path_key_n])

Arguments

<input>: A valid BSON document or an expression that evaluates to a valid BSON document.
<path>: A comma-separated list of dictionary keys or array positions (zero-based index).

Return Type

A string.

Remarks

The BSON string types are returned as is.
The default collation for this function is utf8mb4_bin.
Returns NULL if:
- The extracted value is an invalid BSON string, a BSON type other than string, or NULL.
- The specified path does not exist.

Examples

Note: The following examples explicitly cast string to BSON for clarity.

The following example extracts a string:

SQL

SELECT BSON_EXTRACT_STRING('{"a":{"b":"A valid string"}}':>BSON, 'a', 'b') AS Result;

+----------------+
| Result         |
+----------------+
| A valid string |
+----------------+

The following examples return NULL because of invalid input types:

SQL

SELECT BSON_EXTRACT_STRING('{"a":{"b":{"$numberDecimal":"12.5"}}}':>BSON, 'a', 'b') AS Result;

+--------+
| Result |
+--------+
| NULL   |
+--------+

SQL

SELECT BSON_EXTRACT_STRING('{"a":{"b":{"$date":"2023-03-14T09:48:10.720Z"}}}':>BSON, 'a', 'b') AS Result;

+--------+
| Result |
+--------+
| NULL   |
+--------+

SQL

SELECT BSON_EXTRACT_STRING('{"a":{"b":{"$oid":"641044fd4542e7dc53758df9"}}}':>BSON, 'a', 'b') AS Result;

+--------+
| Result |
+--------+
| NULL   |
+--------+