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visits member for 3 years
seen Aug 24 at 14:04

intentionally left blank


Jan
16
comment Alternative to TEMPORARY tables capable of re-opening in a query?
@a_horse_with_no_name that's a practical idea, but does postgres support this feature for TEMPORARY tables? If yes, I would do this, as there is no solution with mysql.
Jan
14
comment How to UPDATE MAX and MIN of a GROUP BY?
@Mihai sorry that was a typo. The first and last rows in a category if col1='x'
Jan
14
comment How to UPDATE MAX and MIN of a GROUP BY?
@ShlomiNoach in mysql, it is not possible to open a table twice. Thus, it cannot JOINed to itself.
Jan
9
comment Is column order reliable in UPDATE?
I totally understand the unreliability you quoted, but for a simple arithmetic mentioned in the question, a guaranteed order of UPDATE can satisfy the user variable re-SET. Ain't it?
Jan
9
comment Is column order reliable in UPDATE?
@GarethD my case is single table, is there a guarantee that UPDATE is from left to right? as we can use ORDER BY for single table, but not multiple-tables?
Jan
8
comment How to do two actions in conditional UPDATE?
@SebastianMeine sorry I forgot to include the PRIMARY_KEY, which is AUTO_INCREMENT.
Jan
8
comment How to do two actions in conditional UPDATE?
@ypercube I added an example.
Dec
15
comment How to UPDATE a column by COUNT of FK from another table?
does it have any advantage? I use COUNT(*) as I've read it is faster in innoDB comparing with other possibilities including COUNT(primary_key).
Dec
15
comment How to UPDATE a column by COUNT of FK from another table?
is it COUNT(*) ?
Sep
17
comment Do regular ALTERs weaken the performance?
@MaxVernon the project is in beta mode, not alpha. Changes to the database is not about core columns, but additional columns, usually making FK to other tables. The project is conducted based on end-user feedback.
Sep
16
comment Do regular ALTERs weaken the performance?
@MaxVernon I know that it sounds crazy, but it is a live project in which the database structure is about to modified. Unfortunately, due to the rush, we could now extend the test period.
Aug
28
comment Does a TRIGGER improve the performance?
@RaymondNijland innoDB
Aug
27
comment Enabling LOAD DATA LOCAL INFILE in mysql
Thanks for your practical instruction for debugging, what I really needed. In the first step, it revealed, I am on wrong track, as showed local_infile | ON . It seems the problem is not mysql, but PHP or probably the mysql-PHP connector/driver (mysqli).
Aug
26
comment in-memory SQL database system
SQLite is lightweight, but it does not have the mysql server, and in my experience there is no performance advantage over mysql.
Jun
4
comment How to run a SELECT query within while loop in PHP?
as I said, the problem is that there not two tables only. Table 1 is the main table in the query, the second query can be from table2, table3, table4, table5, table6, .... The problem is that PHP arrays are not very efficient for data processing to catch a large set of data into arrays.
May
26
comment Is it possible to force drop of mysql tables with FK?
@ypercube good suggestion of terminology. yes, I want to drop all children, grandchildren; what I need to do manually.
May
26
comment Is it possible to force drop of mysql tables with FK?
@ypercube drop the entire table.
May
22
comment JOIN to read first table and get possible relationship in the second table
@DerekDowney the former one. I added description to the question.
Jan
9
comment How to re-arrange rows to best fit within groups?
This method will change the order in cat, which is the main requirement. It is needed to preserve the order in each category. The flexibility is where categories are mixed.
Dec
22
comment Multiple “GROUP_CONCAT”s with WHERE clause
I think the first solution is simple and elegant and well fit with my need.