유니온쿼리(Union Query)이용 결과값(Result Value) 합치기(Sum)

 

 

유니온쿼리를 이용해서 아래와 같이 2개의 결과값을 합쳐야할 경우 아래와 같이 하면됩니다.

MariaDB [darksharavim]> SELECT count(*) as cnt FROM `wp_usermeta`;
+-----+
| cnt |
+-----+
|  41 |
+-----+
1 row in set (0.001 sec)

MariaDB [darksharavim]> SELECT count(*) as cnt FROM `wp_postmeta`;
+-----+
| cnt |
+-----+
|  39 |
+-----+
1 row in set (0.001 sec)

MariaDB [darksharavim]> select sum(cnt) from (
    -> SELECT count(*) as cnt FROM `wp_usermeta`
    -> union all
    -> SELECT count(*) as cnt FROM `wp_postmeta`
    -> ) as ss;
+----------+
| sum(cnt) |
+----------+
|       80 |
+----------+
1 row in set (0.001 sec)