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How to sum a variable by group
...he syntax behind each alternative. For instance, if I have a larger source table and want to subselect just two dimensions plus summed metrics, can I adapt any of these methods? Hard to tell.
– Dodecaphone
Oct 28 '18 at 10:42
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B-Tree vs Hash Table
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You can only access elements by their primary key in a hashtable.
This is faster than with a tree algorithm (O(1) instead of log(n)), but you cannot select ranges (everything in between x and y).
Tree algorithms support this in Log(n) whereas hash indexes can result in a full table s...
What are the use cases for selecting CHAR over VARCHAR in SQL?
... Another reason is page splits and fragmentation. I had a table with an IDEN PK that got 99% fragmented because of page splits on varchar columns. A very active table and by nature of the application a new row empty row would get created and then populated. Char fixed the fragme...
What is DOM Event delegation?
...efinition.
It refers to handling bubbling events from many elements, like table cells, from a parent object, like the table. It can keep the code simpler, especially when adding or removing elements, and saves some memory.
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What is a stored procedure?
...ut the user will not need to have read/write permissions on the underlying tables. This is a good first step against SQL injection.
Stored procedures do come with downsides, basically the maintenance associated with your basic CRUD operation. Let's say for each table you have an Insert, Update, Del...
Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...foo(x) return x^2 end
foo = function(x) return x^2 end
Table
所谓Table其实就是一个Key Value的数据结构，它很像Javascript中的Object，或是PHP中的数组，在别的语言里叫Dict或Map，Table长成这个样子：
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haoel = {name=...
Invalid default value for 'create_date' timestamp field
...QL'. There set 'SQL_MODE to be used in generated scripts' to "STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" That solves the problem for good.
– sgtdck
Jan 28 '14 at 20:07
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generate days from date range
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This solution uses no loops, procedures, or temp tables. The subquery generates dates for the last 10,000 days, and could be extended to go as far back or forward as you wish.
select a.Date
from (
select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a) + (1000 * d...
How do you check if a certain index exists in a table?
....indexes
WHERE name='YourIndexName' AND object_id = OBJECT_ID('Schema.YourTableName')
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What is your naming convention for stored procedures? [closed]
...hat if the sproc queries information from both the Customer and the Orders table?
– DOK
Oct 26 '08 at 18:27
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