How to Parse JSON in Snowflake

What does PARSE_JSON() do in Snowflake?

PARSE_JSON() takes a VARCHAR string that contains valid JSON and returns a VARIANT value. Once the data is VARIANT, you can use dot or bracket notation, FLATTEN, and other semi-structured functions to query nested objects and arrays.

What is the exact syntax of PARSE_JSON()?

Use PARSE_JSON(string_expr) in a SELECT list, WHERE clause, or as part of an INSERT/UPDATE.The function returns NULL if the string is not valid JSON.

How do I parse a JSON column in an ecommerce table?

Suppose the Orders table has a order_meta VARCHAR column holding JSON like {"payment":"card","shipping":{"speed":"express"}}.Use SELECT PARSE_JSON(order_meta) AS meta FROM Orders; to convert it to VARIANT for easy access.

How do I extract fields after parsing?

Once parsed, reference keys directly: SELECT meta:shipping:speed AS ship_speed FROM (SELECT PARSE_JSON(order_meta) AS meta FROM Orders); returns “express.” Arrays use bracket indices, e.g., items[0].

Can I combine PARSE_JSON() with INSERT?

Yes.Insert parsed JSON into a VARIANT column: INSERT INTO OrderItems_JSON(id, details) SELECT id, PARSE_JSON(raw_json) FROM Staging_OrderItems;

Best practices for PARSE_JSON()

• Validate JSON upstream when possible.
• Store parsed data in VARIANT columns to avoid repeated parsing.
• Index high-use paths with CLUSTER BY.
• Use TRY_PARSE_JSON() if bad input is common.

Common mistakes and fixes

Ignoring invalid JSON errors

Use TRY_PARSE_JSON() or IS_NULL_VALUE checks to prevent query failure.

Re-parsing the same column each query

Materialize PARSE_JSON() into a VARIANT column for performance.

Quick reference table

Function: PARSE_JSON()
Input: VARCHAR JSON string
Output: VARIANT
Error Handling: NULL on invalid input; use TRY_PARSE_JSON() to suppress errors.

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