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Can I change a column from NOT NULL to NULL without dropping it?
... I tried with alter column and it didn't work with the latest mysql server. I tried with modify column and it worked. Strange...
– Kostas Andrianos
Aug 19 '17 at 15:29
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PHP编译configure时常见错误 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...e gmp.h
centos: yum install gmp-devel
14、Configure: error: Cannot find MySQL header files under /usr. Note that the MySQL client library is not bundled anymore!
yum install mysql-devel (For Redhat & Fedora)
# apt-get install libmysql++-dev (For Ubuntu)
15、Configure: error: Please reinstall ...
Cannot issue data manipulation statements with executeQuery()
In MySQL I have two tables, tableA and tableB . I am trying to execute two queries:
10 Answers
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Should I commit or rollback a read transaction?
...timization points for your app. If you're really curious, you can find the mySQL transaction handling code at bazaar.launchpad.net/~mysql/mysql-server/mysql-6.0/annotate/…
– Mark Brackett
May 21 '10 at 15:05
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Error Code: 1005. Can't create table '…' (errno: 150)
...exceeds the maximum length of 64 characters.
For more details, refer to: MySQL Error Number 1005 Can’t create table
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How to execute a raw update sql with dynamic binding in rails
...d try accessing the underlying connection and using it's methods, e.g. for MySQL:
st = ActiveRecord::Base.connection.raw_connection.prepare("update table set f1=? where f2=? and f3=?")
st.execute(f1, f2, f3)
st.close
I'm not sure if there are other ramifications to doing this (connections left op...
云数据及Firebase组件简介 · App Inventor 2 中文网
...据存储。
协作绘图应用程序
这是另一个示例，展示了如何使用 Firebase 将聊天与绘图程序结合起来进行协作草图：Firebase Chat with Interactive Drawing。
FirebaseDB vs TinyWebDB
如果你熟悉 App Inventor 的 TinyWebDB 组件，你会发现 FirebaseDB ...
Why does “_” (underscore) match “-” (hyphen)?
...cluding zero characters).
(From section 3.3.4.7. Pattern Matching in the MySQL documentation.)
If you want to use the underscore in like as a literal, you have to escape it:
select * from a where name like '%taz\_manual%.pdf%';
...
String isNullOrEmpty in Java? [duplicate]
...that when I tried to use StringUtils my IDE (Eclipse) imported it from com.mysql.jdbc.StringUtils which actually has an isNullOrEmpty(myStringObject) method.
ex.
import com.mysql.jdbc.StringUtils;
StringUtils.isNullOrEmpty(host)
Just another alternative for those who already have the MySQL conne...