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Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?
...e - which are typically implemented internally using b-trees (allowing for selecting, sorting or ranges starting from left most column) or hash tables (allowing for selection starting from left most column).
Where the other index types are general-purpose, a FULLTEXT index is specialised, in that it...
How to update column with null value
...Hello');
UPDATE your_table
SET your_column = NULL
WHERE some_id = 1;
SELECT * FROM your_table WHERE your_column IS NULL;
+---------+-------------+
| some_id | your_column |
+---------+-------------+
| 1 | NULL |
+---------+-------------+
1 row in set (0.00 sec)
...
How do I query between two dates using MySQL?
...ember 29 2010 and January 30 2010). Try reversing the order of the dates:
SELECT *
FROM `objects`
WHERE (date_field BETWEEN '2010-01-30 14:15:55' AND '2010-09-29 10:15:55')
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MySQL case insensitive select
Can anyone tell me if a MySQL SELECT query is case sensitive or case insensitive by default? And if not, what query would I have to send so that I can do something like:
...
With MySQL, how can I generate a column containing the record index in a table?
...
You may want to try the following:
SELECT l.position,
l.username,
l.score,
@curRow := @curRow + 1 AS row_number
FROM league_girl l
JOIN (SELECT @curRow := 0) r;
The JOIN (SELECT @curRow := 0) part allows the variable initiali...
How do I check to see if a value is an integer in MySQL?
...e REGEXP operator, matching the string to a regular expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';
this is reasonably fast. If your field is numeric, just test for
ceil(field) = field
instead.
...
MySQL - force not to use cache for testing speed of query
...ACHE (MySQL 5.7) option in your query.
(MySQL 5.6 users click HERE )
eg.
SELECT SQL_NO_CACHE * FROM TABLE
This will stop MySQL caching the results, however be aware that other OS and disk caches may also impact performance. These are harder to get around.
...
MySQL/Amazon RDS error: “you do not have SUPER privileges…”
...e “Parameter Groups” tab.
Create a new Parameter Group. On the dialog, select the MySQL family compatible to your MySQL database version, give it a name and confirm.
Select the just created Parameter Group and issue “Edit Parameters”.
Look for the parameter ‘log_bin_trust_function_creators...
MySQL Query GROUP BY day / month / year
... for added clarity in some cases such as where records span several years. SELECT COUNT(event_id), DATE_FORMAT(event_start, '%Y/%m')
– Ric
Apr 4 '13 at 10:25
...
PDO MySQL: Use PDO::ATTR_EMULATE_PREPARES or not?
... I'm using caches on multiple levels anyway. You can always explicitly use SELECT SQL_CACHE <rest of statement> though.
– Will Morgan
May 4 '12 at 16:37
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