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In MySQL queries, why use join instead of where?
... Performance Perspective:
Where supported (Oracle 9i+, PostgreSQL 7.2+, MySQL 3.23+, SQL Server 2000+), there is no performance benefit to using either syntax over the other. The optimizer sees them as the same query. But more complex queries can benefit from using ANSI-92 syntax:
Ability to ...
Count the number of occurrences of a string in a VARCHAR field?
...test 0
test4 valuevaluevaluevaluevalue 5
I don't have MySQL install, but goggled to find the Equivalent of LEN is LENGTH while REPLACE is same.
So the equivalent query in MySql should be
SELECT TITLE,DESCRIPTION, (LENGTH(DESCRIPTION) - LENGTH(REPLACE(DESCRIPTION, 'value', ''))...
如果携程决心战略性亏损到底，去哪儿怕是只剩一条路可走 - 资讯 - 清泛网 -...
...会入市，而这可能造成携程股价的波动，而对管理层而言如何平稳的过渡获得更高的评级保持股价的稳定增长在一定程度上也是一个挑战。今年2月9日，携程原第一大股东，美国知名老牌共同基金奥本海默基金清空了其持有的所...
MySQL Multiple Joins in one query?
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count(*) vs count(column-name) - which is more correct? [duplicate]
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there is a performance difference (at least in MySQL) as well (see my answer).
– nickf
Jun 9 '10 at 7:51
1
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常用Sql - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
常用Sqlmysql：drop table if exists tablename;不能写成drop table tablename if exists tablename;mysql：建立索引SqlCREATE TABLE t...mysql：drop table if exists tablename;
不能写成
drop table tablename if exists tablename;
mysql：建立索引Sql
CREATE TABLE tablename (
`ID...
PHP的函数前加上“@”的作用 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...供的错误信息屏蔽的专用符号。比如在一个函数前使用@@mysql_query 不会出现Warning，而原来mysql_query 在遇到错误时会在页面上访提示Warning。@是PHP提供的错误信息屏蔽的专用符号。
比如在一个函数前使用@
@mysql_query 不会出现Warning...
Curses library not found. Please install appropriate package - 更多...
Curses library not found. Please install appropriate packageCentOS安装MySql报错：-- Could NOT find Curses (missing: CURSES_LIBRARY CURSES_INCLUDE_PATH)CMake Error at cmake readli...CentOS安装MySql报错：
-- Could NOT find Curses (missing: CURSES_LIBRARY CURSES_INCLUDE_PATH)
CMake Err...
MySQL, update multiple tables with one query
... this one query, of course. You can read more about joins here: http://dev.mysql.com/doc/refman/5.0/en/join.html. There's also a couple restrictions for ordering and limiting on multiple table updates you can read about here: http://dev.mysql.com/doc/refman/5.0/en/update.html (just ctrl+f "join").
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Export to CSV via PHP
...p, $fields);
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First you must load the data from the mysql server in to a array
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