Question

我有以下准备语句，其中我保留了limit子句变量 -

PREPARE fooStmt FROM "SELECT id FROM Table_1 ORDER BY id LIMIT ?";

我定义了一个变量@record -

SET @record = 4;

现在我使用上面的变量来执行预准备语句 -

EXECUTE fooStmt USING @record;

我得到以下结果 -

+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
+----+

现在我的问题是我想要上述结果的最大ID。我尝试了以下查询来获得所需的结果，但它给了我SQL语法错误：

select max(id) from (EXECUTE fooStmt USING @record);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'USING @record)' at line 1

您能帮助我找出问题所在，如何才能得到理想的结果？

Answer 1

请试试这个：

PREPARE fooStmt
FROM "SELECT max(id) AS id FROM ( SELECT id FROM frameThreshold ORDER BY id LIMIT ? ) AS id";

Answer 2

如果你需要，你应该（重新）准备sql

 "select max(id) from 
         (SELECT id FROM Table_1 ORDER BY id LIMIT ?) as t";

然后

 PREPARE your_maxFooStmt FROM  "select max(id) from 
         (SELECT id FROM Table_1 ORDER BY id LIMIT ?) as t";

从执行准备语句结果

2 个答案: