MYSQL错误地使用UPDATE和ORDER BY RAND

Question

我正在尝试使用JOIN和RAND

进行更新

UPDATE table1 a INNER JOIN table2 b USING(id) 
SET a.description = CONCAT('different words', b.name)
WHERE a.description LIKE ''
ORDER BY RAND() LIMIT 100;

我收到错误：UPDATE和ORDER BY的使用不正确

没有加入以下代码完美无缺

UPDATE table1 SET description = CONCAT('different words', name) 
WHERE description LIKE ''
ORDER BY RAND() LIMIT 100;

感谢您的帮助

Answer 1

假设您正在使用String BId = "button1"; // for example int id = getResources().getIdentifier(BId, "id", getPackageName()); // finds R.id.button1 bdatum0 = (Button) findViewById(id); ，您应该将您的查询（使用用户变量和order by）包装为内联视图（MySQL将其称为派生表）。在UPDATE语句中将整个视图引用为行源。所以你的查询应该是这样的：

mysql

Answer 2

试试这个：

 UPDATE a
 SET a.description = CONCAT('different words', b.name)
 FROM table1 a 
 INNER JOIN table2 b ON a.id=b.id 
 WHERE a.description LIKE ''
 ORDER BY RAND() LIMIT 100;