傳遞表名以從光標選擇語句

Question

如何使用從Cursor返回的值作爲mysql過程中的表名？

DECLARE cur CURSOR FOR 
select table_name, column_name 
    from information_schema.columns 
    where table_schema = 'foo' and table_name like 'bar%'; 
OPEN cur; 

loop1: LOOP 

FETCH cur 
INTO table_val, column_val; 

IF no_more_rows THEN 
    CLOSE cur; 
    LEAVE loop1; 
END IF; 
update table_val SET column_val ... 

這會引發錯誤foo.table_val doesnt exist。我如何才能將實際的表名傳遞給select語句？

Answer 1

變化update table_val SET column_val ...到

SET @sql = CONCAT('UPDATE ', table_val, ' SET ', column_val, ' = whatever WHERE...'); 
PREPARE stmt FROM @sql; 
EXECUTE stmt; 
DEALLOCATE PREPARE stmt; 

瞭解更多關於它here。

但請注意，您不能參數化表和列名稱。這隻適用於值。