大约有 40,000 项符合查询结果（耗时：0.0165秒） [XML]
我用AnyComponent块改造了App，30个按钮的代码从300行缩成了10行 - App应用...
...（绿色=空闲，黄色=忙碌，红色=排队）
• 管理员可一键重置所有桌台状态
• 后期还可能增加桌台，不能每次加一个就改一次代码
如果用传统方式，每加一个桌台就是一组新的积木块，20个桌台就会有20个几乎一样的事件块...
How can you determine how much disk space a particular MySQL table is taking up?
...
For a table mydb.mytable run this for:
BYTES
SELECT (data_length+index_length) tablesize
FROM information_schema.tables
WHERE table_schema='mydb' and table_name='mytable';
KILOBYTES
SELECT (data_length+index_length)/power(1024,1) tablesize_kb
FROM information_schema....
ROW_NUMBER() in MySQL
...asy, but actually it kind of isn't).
I often plump for a null-self-join:
SELECT t0.col3
FROM table AS t0
LEFT JOIN table AS t1 ON t0.col1=t1.col1 AND t0.col2=t1.col2 AND t1.col3>t0.col3
WHERE t1.col1 IS NULL;
“Get the rows in the table for which no other row with matching col1,col2 has a hi...
Set operations (union, intersection) on Swift array?
...ing> = Set(array2)
Swift 3.0+ can do operations on sets as:
firstSet.union(secondSet)// Union of two sets
firstSet.intersection(secondSet)// Intersection of two sets
firstSet.symmetricDifference(secondSet)// exclusiveOr
Swift 2.0 can calculate on array arguments:
set1.union(array2) //...
How do I split a string so I can access item x?
...0,
PATINDEX('%|%', @products))
SELECT @individual
SET @products = SUBSTRING(@products,
LEN(@individual + '|') + 1,
LEN(@products))
END
ELSE
BEGIN
SET @individu...
Should I use the datetime or timestamp data type in MySQL?
...o with the native format. You can do calculations within MySQL that way
("SELECT DATE_ADD(my_datetime, INTERVAL 1 DAY)") and it is simple to change the format of the value to a UNIX timestamp ("SELECT UNIX_TIMESTAMP(my_datetime)") when you query the record if you want to operate on it with PHP.
...
Union of dict objects in Python [duplicate]
How do you calculate the union of two dict objects in Python, where a (key, value) pair is present in the result iff key is in either dict (unless there are duplicates)?
...
Joining two lists together
...eserves the order of the lists, but it doesn't remove any duplicates which Union would do.
This does change list a. If you wanted to preserve the original lists then you should use Concat (as pointed out in the other answers):
var newList = a.Concat(b);
This returns an IEnumerable as long as a i...
Detect if value is number in MySQL
...
This should work in most cases.
SELECT * FROM myTable WHERE concat('',col1 * 1) = col1
It doesn't work for non-standard numbers like
1e4
1.2e5
123. (trailing decimal)
share
...
How to see indexes for a database or table in MySQL?
...pecific schema you can use the STATISTICS table from INFORMATION_SCHEMA:
SELECT DISTINCT
TABLE_NAME,
INDEX_NAME
FROM INFORMATION_SCHEMA.STATISTICS
WHERE TABLE_SCHEMA = 'your_schema';
Removing the where clause will show you all indexes in all schemas.
...