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关于我们 · App Inventor 2 中文网，少儿编程陪伴者
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Is the primary key automatically indexed in MySQL?
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According to http://dev.mysql.com/doc/refman/5.0/en/constraint-primary-key.html it would appear that this is would be implicit
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Convert from MySQL datetime to another format with PHP
I have a datetime column in MySQL.
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MySQL: Large VARCHAR vs. TEXT?
I've got a messages table in MySQL which records messages between users. Apart from the typical ids and message types (all integer types) I need to save the actual message text as either VARCHAR or TEXT. I'm setting a front-end limit of 3000 characters which means the messages would never be inserte...
MySQL select one column DISTINCT, with corresponding other columns
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@Full Decent you can't, according to MySQL documentation: "The server is free to choose any value from each group, so unless they are the same, the values chosen are indeterminate.". In practice I've successfully used this kind of queries with ORDER BY clause, ...
python-pandas and databases like mysql
...ing a DBI compatible library. We can look at two short examples using the MySQLdb and cx_Oracle libraries to connect to Oracle and MySQL and query their data dictionaries. Here is the example for cx_Oracle:
import pandas as pd
import cx_Oracle
ora_conn = cx_Oracle.connect('your_connection_string'...
VIP会员中心 · App Inventor 2 中文网，少儿编程陪伴者
... 我家孩子在App Inventor 2 中文网的少儿编程课程中学到了如何设计自己的App，现在他已经可以独立开发一些简单的小应用了。很高兴看到他对于编程的兴趣和自信的提升！ ...
ERROR: Error 1005: Can't create table (errno: 121)
I have troubles with forward engineering my MySQL database into WAMP server..
I was going to post an image of the schema but as this is my first post I can't.
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select * vs select column
...the top of my head is when you want only the value of an indexed column in MySQL (for example, just to check for row existence), and you're using MyISAM storage engine, it'll grab the data from the MYI file, which could be in memory, and not even go to disk!
– Mike Sherov
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MySQL Conditional Insert
...his, dual is a table with one row only (found originally in Oracle, now in mysql too). The logic is that the SELECT statement generates a single row of data with the required values, but only when the values are not already found.
Alternatively, look at the MERGE statement.
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