Scalar Functions — JSON / Dynamic

KQL treats JSON objects and arrays as first-class dynamic values. These functions let you extract fields, pack values into objects or arrays, and serialize dynamic data back to JSON strings. Dotted property access (obj.field) is supported across all dialects and is rewritten as a json_extract_string call automatically.

Legend: ✅ Supported · ⚠️ Approximated · ❌ Not Supported · 🔄 Rewritten

Function	SQLite	MySQL	ClickHouse	PostgreSQL	Notes
`json_extract_string()`	✅	✅	✅	✅	`json_extract` / `JSONExtractString` / `->>`
`json_extract_raw()`	✅	✅	✅	✅	`json_extract` / `JSONExtractRaw` / `->`
`dynamic_to_json()`	❌	❌	✅	✅	ClickHouse: `toJSONString`; Postgres: CAST to text
`parse_json()`	❌	✅	✅	✅
`bag_pack()` / `pack()`	✅	✅	✅	✅	`json_object` / `jsonb_build_object` / `map()`
`pack_all()`	❌	❌	❌	❌	Dynamic column enumeration has no SQL equivalent
`pack_array()`	❌	❌	✅	✅	ClickHouse: `array()`; Postgres: `ARRAY()`
`bag_keys()`	❌	❌	✅	❌	ClickHouse: `mapKeys()`
`bag_merge()`	❌	❌	✅	❌	ClickHouse: `mapMerge()`
Dotted property access `obj.field`	✅	✅	✅	✅	Mapped to `json_extract_string`