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Get records with max value for each group of grouped SQL results
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There's a super-simple way to do this in mysql:
select *
from (select * from mytable order by `Group`, age desc, Person) x
group by `Group`
This works because in mysql you're allowed to not aggregate non-group-by columns, in which case mysql just returns the first...
Difference between VARCHAR and TEXT in MySQL [duplicate]
When we create a table in MySQL with a VARCHAR column, we have to set the length for it. But for TEXT type we don't have to provide the length.
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How to get UTF-8 working in Java webapps?
...s" those characters.
To get UTF-8 working under Java+Tomcat+Linux/Windows+Mysql requires the following:
Configuring Tomcat's server.xml
It's necessary to configure that the connector uses UTF-8 to encode url (GET request) parameters:
<Connector port="8080" maxHttpHeaderSize="8192"
maxThreads...
MySQL Update Inner Join tables query
I have no idea what the problem is. Using MySQL 5.0 I get a compile error when attempting to run the following MySQL update query:
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MySQL: @variable vs. variable. What's the difference?
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MySQL has a concept of user-defined variables.
They are loosely typed variables that may be initialized somewhere in a session and keep their value until the session ends.
They are prepended with an @ sign, like this: @var
Yo...
How to Get True Size of MySQL Database?
I would like to know how much space does my MySQL database use, in order to select a web host.
I found the command SHOW TABLE STATUS LIKE 'table_name' so when I do the query, I get something like this:
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MySQL load NULL values from CSV data
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MySQL manual says:
When reading data with LOAD DATA
INFILE, empty or missing columns are
updated with ''. If you want a NULL
value in a column, you should use \N
in the data file. The literal word
“NULL” ma...
Error 1046 No database Selected, how to resolve?
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You need to tell MySQL which database to use:
USE database_name;
before you create a table.
In case the database does not exist, you need to create it as:
CREATE DATABASE database_name;
followed by:
USE database_name;
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What's the difference between utf8_general_ci and utf8_unicode_ci?
...ncoding. The differences are in how text is sorted and compared.
Note: In MySQL you have to use utf8mb4 rather than utf8. Confusingly, utf8 is a flawed UTF-8 implementation from early MySQL versions which remains only for backward compatibility. The fixed version was given the name utf8mb4.
Note: N...
MFC中ComboBox控件的使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
MFC中ComboBox控件的使用一、如何添加 删除Combo Box内容1，在ComboBox控件属性的Data标签里面添加，一行表示ComboBox下拉列表中的一行。换行用ctrl+回车。2，在程...一、如何添加/删除Combo Box内容
1，在ComboBox控件属性的Data标签里面添...