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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！ ...
Set value to NULL in MySQL
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You're probably quoting 'NULL'. NULL is a reserved word in MySQL, and can be inserted/updated without quotes:
INSERT INTO user (name, something_optional) VALUES ("Joe", NULL);
UPDATE user SET something_optional = NULL;
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MySQL ON DUPLICATE KEY - last insert id?
...heck this page out: https://web.archive.org/web/20150329004325/https://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html
At the bottom of the page they explain how you can make LAST_INSERT_ID meaningful for updates by passing an expression to that MySQL function.
From the MySQL documentation...
No module named MySQLdb
I am using Python version 2.5.4 and install MySQL version 5.0 and Django. Django is working fine with Python, but not MySQL. I am using it in Windows Vista.
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MySQL error code: 1175 during UPDATE in MySQL Workbench
I'm trying to update the column visited to give it the value 1. I use MySQL workbench, and I'm writing the statement in the SQL editor from inside the workbench. I'm writing the following command:
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MySQL 'create schema' and 'create database' - Is there any difference
... between the create schema command and the create database command for MySQL.
6 Answers
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App Inventor 2 列表代码块 · App Inventor 2 中文网
...用给定的变量名称 item 来引用当前列表项。
此处 是有关如何使用该块的教程。
创建过滤列表
通过保持输入列表中的每个项目满足测试来创建一个新列表。
主体是一个布尔表达式，用于检查项目是否通过...
MySQL: Insert record if not exists in table
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if you need to get warning message you can afterwards do mysql> show warnings\G
– fiorentinoing
Oct 20 '16 at 18:59
2
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App Inventor 2 中文网原创内容 · App Inventor 2 中文网
...科普】App Inventor 2 添加超过10个屏幕会怎样？
【算法】如何计算1加到100的总和？（经典循环的写法）
【算法】App Inventor 2 算法之二分算法（Binary Search）实现，快速查找定位
组件用法
【微数据库】每次打开app时保持上一...
add column to mysql table if it does not exist
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Note that INFORMATION_SCHEMA isn't supported in MySQL prior to 5.0. Nor are stored procedures supported prior to 5.0, so if you need to support MySQL 4.1, this solution isn't good.
One solution used by frameworks that use database migrations is to record in your database...