mysql> WITH RECURSIVE cte
,,,,,(
,,,,,,,SELECT 1, AS n, & # 39; abc # 39; AS str
,,,,,,UNION 所有
,,,,,,,SELECT n +, 1, CONCAT (str, str),得到cte WHERE n & lt; 3
,,,,,)
,,,,,SELECT *,得到cte;
ERROR 1406, (22001):, Data too long for column & # 39; str # 39; at row 1
mysql> WITH RECURSIVE cte
,,,,,(
,,,,,,,SELECT 1, AS n,,演员(& # 39;abc # 39;, AS CHAR (20)), AS str
,,,,,,UNION 所有
,,,,,,,SELECT n +, 1, CONCAT (str, str),得到cte WHERE n & lt; 3
,,,,,)
,,,,,SELECT *,得到cte;
+ - - - - - - - - - - - - - - - - - - - - - - +
|,n ,,, |, str ,,,,,,,, |
+ - - - - - - - - - - - - - - - - - - - - - - +
|,,,,1,|,abc ,,,,,,,, |
|,,,,2,|,abcabc ,,,,, |
|,,,,3,|,abcabcabcabc |
+ - - - - - - - - - - - - - - - - - - - - - - +
3,rows set 拷贝;(0.00,sec)
当调用cte为1001次的时候,查询报的错
mysql>, WITH RECURSIVE cte (n),
,,,,,(
,,,,,,,SELECT 1
,,,,,,UNION 所有
,,,,,,,SELECT n +, 1,得到cte where n<1001
,,,,,)
,,,,,SELECT *,得到cte;
ERROR 3636, (HY000):, Recursive query aborted after 1001年,迭代只Try increasing @@cte_max_recursion_depth 用a larger 价值。
把参数设置为5 s,执行超时并报错:
mysql>, SET max_execution_time =, 5000;,, # 5 s
Query 好吧,,0,rows affected (0.00,秒)
mysql>, select s。*,得到salaries s where s.emp_no 拷贝(select emp_no 得到employees e where e.first_name=& # 39;格奥尔基# 39;,union all select emp_no 得到employees e where e.hire_date=& # 39; 1992 - 12 - 18 & # 39;);
ERROR 3024, (HY000):, Query execution was 中断,,maximum statement execution time 超过
把参数设置为50年代,执行成功:
SET max_execution_time =, 50000;
mysql>, select s。*,得到salaries s where s.emp_no 拷贝(select emp_no 得到employees e where e.first_name=& # 39;格奥尔基# 39;,union all select emp_no 得到employees e where e.hire_date=& # 39; 1992 - 12 - 18 & # 39;);
2718年,rows set 拷贝;(21.70,sec)
