大约有 40,000 项符合查询结果（耗时：0.0354秒） [XML]
How to do a regular expression replace in MySQL?
...ositions and perform substring substitution and extraction, respectively.
SELECT REGEXP_REPLACE('Stackoverflow','[A-Zf]','-',1,0,'c');
-- Output:
-tackover-low
DBFiddle Demo
share
|
improve this ...
MySQL indexes - what are the best practices?
...t them. Generally I put an index on any fields that I will be searching or selecting using a WHERE clause but sometimes it doesn't seem so black and white.
...
MySQL OPTIMIZE all tables?
...>.<your_table>;, optimize all tables in a given schema like this: select concat('OPTIMIZE NO_WRITE_TO_BINLOG TABLE ',table_schema,'.',table_name,';') into outfile '/tmp/optimize_all_tables.sql' from information_schema.tables where table_schema = 'pabeta' and table_type = 'base table'; sourc...
Check if a class has a member function of a given signature
...her down
Check for member x in a given class. Could be var, func, class, union, or enum:
CREATE_MEMBER_CHECK(x);
bool has_x = has_member_x<class_to_check_for_x>::value;
Check for member function void x():
//Func signature MUST have T as template variable here... simpler this way :\
CREAT...
Convert timestamp to date in MySQL query
...
SELECT * FROM users WHERE DATE_FORMAT(FROM_UNIXTIME(users.user_created_at),'%Y-%b-%e') = '2015-03-06' is this correct format or should i modify this?
– Dheeraj Thedijje
Mar 7 '18 at 11:4...
来自微软的一手内幕：Windows 10是怎么出炉的 - 创意 - 清泛网 - 专注C/C++及内核技术
...，将代替每隔几年的大升级。微软未必真知道，此举终将如何收场，但Windows 10的出现，注定成为一个里程碑。
这家公司将再不能承受Windows 8式失误造成的恶果
这里程碑不同以往。即便Windows 10已经发布，也不算万事大...
Cast int to varchar
...datatype, there is no varchar datatype that you can cast/convert data to:
select CAST(id as CHAR(50)) as col1
from t9;
select CONVERT(id, CHAR(50)) as colI1
from t9;
See the following SQL — in action — over at SQL Fiddle:
/*! Build Schema */
create table t9 (id INT, name VARCHAR(55));
ins...
MYSQL OR vs IN performance
...for future Googlers. Total count of returned results is 7264 out of 10000
SELECT * FROM item WHERE id = 1 OR id = 2 ... id = 10000
This query took 0.1239 seconds
SELECT * FROM item WHERE id IN (1,2,3,...10000)
This query took 0.0433 seconds
IN is 3 times faster than OR
...
What's the difference between array_merge and array + array?
...
The difference is:
The + operator takes the union of the two arrays, whereas the array_merge function takes the union BUT the duplicate keys are overwritten.
share
|
i...
MySQL query String contains
...
Quite simple actually:
mysql_query("
SELECT *
FROM `table`
WHERE `column` LIKE '%{$needle}%'
");
The % is a wildcard for any characters set (none, one or many). Do note that this can get slow on very large datasets so if your database grows you'll need to use ...