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How to get multiple counts with one SQL query?
... entire nested query with a simple count(*) as @Mihai shows - with further MySQL only syntax simplifications.
– YoYo
Apr 1 '17 at 19:29
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T-SQL: Opposite to string concatenation - how to split string into multiple records [duplicate]
... Pieces(pn, start, stop) AS (
SELECT 1, 1, CHARINDEX(@sep, @s)
UNION ALL
SELECT pn + 1, stop + 1, CHARINDEX(@sep, @s, stop + 1)
FROM Pieces
WHERE stop > 0
)
SELECT pn,
SUBSTRING(@s, start, CASE WHEN stop > 0 THEN stop-start ELSE 512 END) AS s
FRO...
LR性能测试结果样例分析 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...是否达到了预期的性能指标，其中又有哪些性能隐患，该如何解决。
图1- 1性能测试结果分析流程图
结果摘要
LoadRunner进行场景测试结果收集后，首先显示的该结果的一个摘要信息，如图1- 2所示。概要中列出了场景执行...
1052: Column 'id' in field list is ambiguous
...ection
FROM tbl_names
NATURAL JOIN tbl_section
See also: https://dev.mysql.com/doc/refman/5.7/en/join.html
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How do I get SUM function in MySQL to return '0' if no values are found?
Say I have a simple function in MySQL:
4 Answers
4
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'IF' in 'SELECT' statement - choose output value based on column values
...IF(type = 'P', amount, amount * -1) as amount
FROM report
See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html.
Additionally, you could handle when the condition is null. In the case of a null amount:
SELECT id,
IF(type = 'P', IFNULL(amount,0), IFNULL(amount,0) * -1) as...
How can you represent inheritance in a database?
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Does other DBs support INHERITS besides PostgreSQL ? MySQL for example ?
– giannis christofakis
Mar 11 '16 at 9:00
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手把手教你如何加入主流DSP广告联盟 - 更多技术 - 清泛网 - 专注C/C++及内核技术
手把手教你如何加入主流DSP广告联盟打造好自己的网站后，考虑后续的持续运营，可能需要引入互联网广告。前期由于网站知名度不高，最好挂一些联盟广告，它会根据用户的浏览记录自动推荐相应广告内容，对于站长来说也比...
Get top n records for each group of grouped results
...g this: The version is the variables is close to being correct. However, MySQL does not guarantee the order of evaluation of expressions in the SELECT (and, in fact, sometimes evaluates them out-of-order). The key to the solution is to put all the variable assignments in a single expression; here...