代码语言:javascript 代码运行次数:0 运行 AI代码解释 mysql>USEstatistics;mysql>EXPLAINFORMAT=TREEFORSCHEMAcustomer1SELECTname,quantityFROMordersJOINitemsONorders.item_id=items.id;->Nested loop innerjoin(cost=2.3rows=5)->Table scan onitems(cost=0.55rows=3)->Index lookup on orders usingfk_item_id(i...
MySQL explains how it would process the statement, including information about how tables are joined and in which order. For information about using EXPLAIN to obtain execution plan information, see Section 8.8.2, “EXPLAIN Output Format”. 当...
I have used for... of loop on string it works But when I applied it on window object it console an error that window object is not iterable. How both the objects are different ?? As we know string is also an object in js.
PHP foreach loop array I have a script where it's displaying user info on a leader board. It's grabbing each user's display info through the 'registrations' table as shown in the top sql, however their back-end info (userna... ...
for(leti=0;i<myList.length;i+=1);/* The for loop is one of the loops you can use in javascript to run a line or multiple codes for a repeated amount of duration.In this case, you have created a variable called i and stored the value 0 to it. You then said in your code: ru...
Settimout not working inside For loop, acting weird? Im trying to simulate a Typewriter effect with javascript. Theorically it should work with my code: That should be it, when i call TypeWrite("example", "p_test"); it should write e... ...
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. ...
Using join buffer : 使用了连接缓存,Block Nested Loop,连接算法是块嵌套循环连接;Batched Key Access,连接算法是批量索引连接。 Using where : 表示 MySQL 服务器从存储引擎收到查询数据,再进行 “后过滤”(Post-filter)。所谓 “后过滤”,就是先读取整行数据,再检查此行是否符合 where 句的条件,符合就留下...
Using index for skip scan 表示使用了Skip Scan。详见Skip Scan Range Access Method 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javascript:void(0) ...
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