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cartesian product in pandas
...w, then you can produce a cartesian product using merge (like you would in SQL).
from pandas import DataFrame, merge
df1 = DataFrame({'key':[1,1], 'col1':[1,2],'col2':[3,4]})
df2 = DataFrame({'key':[1,1], 'col3':[5,6]})
merge(df1, df2,on='key')[['col1', 'col2', 'col3']]
Output:
col1 col2 c...
Adding n hours to a date in Java?
...er compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Jav...
How to get number of rows using SqlDataReader in C#
My question is how to get the number of rows returned by a query using SqlDataReader in C#. I've seen some answers about this but none were clearly defined except for one that states to do a while loop with Read() method and increment a counter.
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MySQL's now() +1 day
I'm using now() in MySQL query.
4 Answers
4
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Difference between FetchType LAZY and EAGER in Java Persistence API?
...eferred" at the child entity. When I say course.getStudents(), it fires an SQL query( saw that on console). In Lazy fetch type also, same thing happens. So, What's is the difference??
– Neha Choudhary
Jan 3 '13 at 3:59
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Django South - table already exists
...uent new migration, when it called _remake_table(), was throwing the error sqlite3.pypysqlite2.dbapi2.OperationalError: table "_south_new_myapp_mymodel" already exists, because it did already exist and wasn't supposed to be there.
The _south_new bit looked odd to me, so I browsed my DB, saw the tab...
Java: getMinutes and getHours
...er compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
J...
Changing Java Date one hour back
...er compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
J...
How can I transform string to UTF-8 in C#?
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If you want to save any string to mysql database do this:->
Your database field structure i phpmyadmin [ or any other control panel] should set to utf8-gerneral-ci
2) you should change your string [Ex. textbox1.text] to byte, therefor
2-1) define byte[] s...
腾讯Tencent开源框架介绍（持续更新） - 开源 & Github - 清泛网 - 专注C/C++及内核技术
...付、公众平台等多个重要业务。
https://github.com/Tencent/phxsql PhxSQL是由微信后台团队自主研发的一款数据强一致、服务高可用的分布式数据库服务。PhxSQL提供Zookeeper级别的强一致和高可用，完全兼容MySQL。
https://github.com/Tencent/phx...