How does let in for loop work? I understand how "var" works and I'm quite used to it - the scope is functional. However the let statement is far from clear. I understand is has block scope, but why does THAT matter in the......
32 Using index for skip scan 表示使用了Skip Scan。详见Skip Scan Range Access Method 33 Using join buffer (Block Nested Loop), Using join buffer (Batched Key Access) 使用Block Nested Loop或Batched Key Access算法提高join的性能。详见https://www.cnblogs.com/chenpingzhao/p/6720531.html 34 Using...
代码运行次数:0 mysql>explain select*from emp e where e.deptnoin(select d.deptno from dept d where d.dname='SALEDept');+---+---+---+---+---+---+---+---+---+---+---+---+|id|select_type|table|partitions|type|possible_keys|key|key_len|ref|rows|filtered|Extra|+---+-...
I've got following code I want to execute the query first and then return result. How should I do it. I've also done it with simple for loop but does not work. I think you just need to call next() aft... what is the difference between \c and \\c?
32 Using index for skip scan 表示使用了Skip Scan。详见 Skip Scan Range Access Method[13] 33 Using join buffer (Block Nested Loop), Using join buffer (Batched Key Access) 使用Block Nested Loop或Batched Key Access算法提高join的性能。详见 https://www.cnblogs.com/chenpingzhao/p/6720531.html[...
The 'do-while' loop can be implemented (in C) as: inti=5; do { printf("%d",i); i--; }while(i>=0); where 'i' is the loop variable. Answer and Explanation:1 Both for loop and while loop can run multiple statements in successive repetition efficiently. ...
UNCACHEABLE SUBQUERY A subquery for which the result cannot be cached and must be re-evaluated for each row of the outer query UNCACHEABLE UNION The second or later select in a UNION that belongs to an uncacheable subquery (see UNCACHEABLE SUBQUERY) SIMPLE 查询语句中不包含UNION或者子查询的...
FOR i IN (SELECT other_xml FROM gv$sql_plan WHERE sql_id = TRIM('&&sql_id.') AND plan_hash_value = TO_NUMBER(TRIM('&&plan_hash_value.')) AND other_xml IS NOT NULL ORDER BY child_number, id) LOOP :other_xml := i.other_xml; ...
Explain array in java. Explain the difference between while loop and for loop? Give an example for the while loop and the for loop. Write the following code #pragma warning(disable: 4996) int getNum(void) { /* the array is 121 bytes in size; we'll see in a later lecture how we ...
1 row in set (0.00 sec) 如果此时在当前会话中获取执行计划,将会返回错误信息: mysql> EXPLAIN FOR CONNECTION 30; ERROR 3012 (HY000): EXPLAIN FOR CONNECTION command is supported only for SELECT/UPDATE/INSERT/DELETE/REPLACE 因为只有 SELECT、UPDATE、INSERT、DELETE、REPLACE 语句支持执行计划,当前正在执行...