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How do I insert NULL values using PDO?
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I had trouble with PDO::PARAM_NULL on MySql 5.1.53, but PDO::PARAM_INT with a null value worked great.
– Will Shaver
Dec 5 '11 at 19:33
2
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Best practices for SQL varchar column length [closed]
... table's varchar column. But I could not find any reference for that.
For MySQL the manual says "In most cases, ALTER TABLE makes a temporary copy of the original table". And my own tests confirm that: running an ALTER TABLE on a table with 1.2 million rows (the same as in my test with Postgres) to...
INSERT INTO…SELECT for all MySQL columns
...%2f%2fstackoverflow.com%2fquestions%2f5253302%2finsert-into-select-for-all-mysql-columns%23new-answer', 'question_page');
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SHFileOperation函数总结（文件夹的移动、复制、删除） - C/C++ - 清泛网 -...
...r.exe保存被重命名的文件,以避免文件名冲突!
上面知道了如何才能使hNameMappings有效
现在如何使用hNameMappings,及其所指的结构大小?并取得这个内存块的内容呢?
hNameMappings 是简单LPVOID无法使用loop
要使用hNameMappings，必须定义一个...
LIMIT 10..20 in SQL Server
... not part of standard SQL. It's supported as a vendor extension to SQL by MySQL, PostgreSQL, and SQLite.
Other brands of database may have similar features (e.g. TOP in Microsoft SQL Server), but these don't always work identically.
It's hard to use TOP in Microsoft SQL Server to mimic the LIMI...
UTF-8: General? Bin? Unicode?
...only one-to-one comparisons between characters.
Quoted from:
http://dev.mysql.com/doc/refman/5.0/en/charset-unicode-sets.html
For more detailed explanation, please read the following post from MySQL forums:
http://forums.mysql.com/read.php?103,187048,188748
As for utf8_bin:
Both utf8_general_ci...
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(*) 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
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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...