mysql - 使用 MySQL 用户定义的变量在 UPDATE 语句上连接表名

Question

我正在尝试为UPDATE语句设置表名的前缀。我必须UPDATE在多个数据库上运行此语句数十次，每个数据库都有不同的表前缀。

下面的代码不起作用，但这是我想要完成的想法。

SET @prefix = 'prefix_';
SET @old = "old_value";
SET @new = "new_value";
UPDATE CONCAT(@prefix, 'table1') SET some_field = REPLACE(some_field, @old, @new);
UPDATE CONCAT(@prefix, 'table2') SET some_field = REPLACE(some_field, @old, @new);
UPDATE CONCAT(@prefix, 'table3') SET some_field = REPLACE(some_field, @old, @new);

手动编写将是...

UPDATE prefix_table1 SET some_field = REPLACE(some_field, 'old_value', 'new_value');
UPDATE prefix_table2 SET some_field = REPLACE(some_field, 'old_value', 'new_value');
UPDATE prefix_table3 SET some_field = REPLACE(some_field, 'old_value', 'new_value');

Answer 1

用Dynamic SQL在这个上，

SET @prefix = 'prefix_';
SET @old = "old_value";
SET @new = "new_value";

SET @sql1 = CONCAT('UPDATE ', @prefix, 'table1 SET some_field = REPLACE(some_field,?,?)');
SET @sql2 = CONCAT('UPDATE ', @prefix, 'table2 SET some_field = REPLACE(some_field,?,?)');
SET @sql3 = CONCAT('UPDATE ', @prefix, 'table3 SET some_field = REPLACE(some_field,?,?)');

PREPARE stmt1 FROM @sql1;
PREPARE stmt2 FROM @sql2;
PREPARE stmt3 FROM @sql3;

EXECUTE stmt1 USING @old, @new;
EXECUTE stmt2 USING @old, @new;
EXECUTE stmt3 USING @old, @new;

DEALLOCATE PREPARE stmt1;
DEALLOCATE PREPARE stmt2;
DEALLOCATE PREPARE stmt3;

• 准备好的报表