Function sqlJsonHasKey

Does the JSON object in expr have the given top-level (or path-qualified, dotted) key?

• mysql/mariadb: JSON_CONTAINS_PATH(col, 'one', '$.key') (matches buildJsonHasKey in src/dialects/{mysql,mariadb}/index.ts).
• postgres/cockroachdb: native ? key-existence operator -> col ? 'key' (top-level keys only, matching jsonb semantics).
• sqlite: json_extract(col, '$.key') IS NOT NULL (matches buildJsonHasKey in src/dialects/sqlite/index.ts).
• mssql: JSON_VALUE(col, '$.key') IS NOT NULL (standard SQL Server workaround pattern; note this cannot distinguish "key present with a JSON null value" from "key absent").
• oracle: JSON_EXISTS(col, '$.key').
• snowflake: ARRAY_CONTAINS('key'::VARIANT, OBJECT_KEYS(col)).
• redshift: SUPER dot-navigation returns SQL NULL for missing attributes, so col.key IS NOT NULL reliably detects key presence.
• db2: JSON_EXISTS(col, '$.key') (Db2 11.5+ JSON path predicates).
• clickhouse: JSONHas(col, 'key').