使用子查询将mySQL查询转换为带子查询的DB2 SQL查询

Question

我对DB2 SQL服务器很不熟悉。我试图从多个表中查询总rowCount，如下所示：

SELECT
 SUM(COUNT)
  AS ROWS
 FROM
 (SELECT COUNT(*) AS COUNT FROM TABLE1
 UNION ALL
SELECT COUNT(*) AS COUNT FROM TABLE2
 UNION ALL
SELECT COUNT(*) AS COUNT FROM TABLE3
 UNION ALL
//ETC...
)

但是它一直在标记语法错误＆＃34;）＆＃34;。我将如何重组这个？

Answer 1

DB2（和SQL Server）要求子查询具有别名，因此：

SELECT
 SUM(COUNT)
  AS ROWS
 FROM
 (SELECT COUNT(*) AS COUNT FROM TABLE1
 UNION ALL
SELECT COUNT(*) AS COUNT FROM TABLE2
 UNION ALL
SELECT COUNT(*) AS COUNT FROM TABLE3
 UNION ALL
//ETC...
) as subqueryAlias