EC
3612
MariaDBERRORNotableQueryHIGH confidence

Table function cannot be used over a UNION

Production Risk

Medium — Query fails; JSON processing pipelines may be disrupted.

How to reproduce
trigger — this will error
trigger — this will error
SELECT * FROM JSON_TABLE('[1,2]', '$[*]' COLUMNS (v INT PATH '
#x27;)) jt
UNION
SELECT * FROM JSON_TABLE('[3,4]', '$[*]' COLUMNS (v INT PATH '
#x27;)) jt2;

expected output

ERROR 3612 (HY000): Table function cannot be resolved over a UNION.

Fix

Use subqueries with UNION

Use subqueries with UNION
SELECT v FROM (SELECT * FROM JSON_TABLE('[1,2]', '$[*]' COLUMNS (v INT PATH '
#x27;)) jt) sub1
UNION ALL
SELECT v FROM (SELECT * FROM JSON_TABLE('[3,4]', '$[*]' COLUMNS (v INT PATH '
#x27;)) jt2) sub2;

Why this works

Wraps each table function in a derived table before the UNION.

What not to do

✕

Version notes

Sources
Official documentation ↗

MySQL 8.0 — 3612 ER_UNRESOLVED_TABLE_FUNCTION_OVER_UNION

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