2009年10月23日 · I am building an export file to be loaded into a sales reporting tool using SELECT . . . INTO OUTFILE. The query joins 4 tables and left joins 1 table. When I added the left join, the query execution time went from 20 seconds to roughly 2 …

2018年4月1日 · I'm trying to create a statement to join my tables. and to calculate with the values. Target table: timestamp a.value b.value diff 2018-03-30 00:01:00 100 10 90 2018-03-30 00:02:02 200 60 140 the callenge for me is, to get the clostest time value to do the join.

2008年8月20日 · mysql> insert into `a` values ('1'); mysql> select *, @x := 1 from `a` as t1 left join `a` as t2 on 5 = @x left join `a` as t3 on 0 = 1 ; #1120 - Cross dependency found in OUTER JOIN; examine your ON conditions

2009年3月24日 · When I use DISTINCT in an INNER JOIN query that returns more than 1 column in the SELECT a full table scan is performed rather than using an index. When 1 column is returned in the SELECT the index is used. (1) Create the following tables: CREATE TABLE tab1 ( col1 int NOT NULL, col2 varchar(24) NOT NULL, col3 int NOT NULL,

2009年1月15日 · Mi chiamo Emiliano ed è la prima volta che scrivo su questo forum per un problema con MySQL. Il problema riguarda i join. Per semplicità scrivo direttamente il codice: select c.cod_barre,v.cod_barre from vendita c left join (vendita v) on (c.cod_barre=v.cod_barre) where v.cod_barre<>931;

2009年1月8日 · Can someone tell me How I can join a table (A) on a table (B) on a sorted column using a join condition so that only the first match is selected as the joined record? For instance, I have: Table A phone numbers 983357654 Table B Prefixes 9833 983 98 9

2013年7月2日 · This leads to the JOIN doing full table scans to connect the two temp tables. At worst, each subquery is 18K rows, so the JOIN would be doing 18K*18K = 324M operations, which will take time. At best, each subquery would shrink (because of GROUP BY) to only one row; but then you would not be asking the question.

2012年3月10日 · My question is whether it's possible to write this kind of query (or change the indexes/tables) in such a way that would allow MySQL to figure out the best way to execute it? I would like to keep the time under 100 ms, regardless of the filter params. Thank you, Nikita NOTE: I'm using MySQL 5.1.55-winx64 with the my-huge.ini config.

2006年8月2日 · MySQL JOIN Problem. Posted by: sean g Date: June 29, 2006 08:01AM Hi, I have 2 tables and im doing a left ...

2022年8月7日 · I can't DELETE FROM posts USING users LEFT JOIN ... because MySQL doesn't support LIMIT in this case. It seems like I have these options: 1. Load bob's user_id first and use the delete/limit query without any joins. This seems easiest. 2. Use a subquery DELETE FROM posts WHERE postId IN (SELECT users...) LIMIT 5000 3.