UNION
description
複数の集約中間結果を1つに集約します。 結果の型はagg_stateで、関数シグネチャは入力パラメータと一致します。
Syntax
AGGREGATE_FUNCTION_UNION(agg_state)
example
mysql [test]>select avg_merge(t) from (select avg_union(avg_state(1)) as t from d_table group by k1)p;
+----------------+
| avg_merge(`t`) |
+----------------+
| 1 |
+----------------+
keywords
AGG_STATE、UNION