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How can I get enum possible values in a MySQL database?
...wns with enum possible values from a DB automatically. Is this possible in MySQL?
24 Answers
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Comparing two dictionaries and checking how many (key, value) pairs are equal
...t(json.dumps(diff, indent=4))
Output
{
"values_changed": {
"root['a']": {
"new_value": 2,
"old_value": 1
},
"root['nested']['b']": {
"new_value": 2,
"old_value": 1
}
}
}
Note about pretty-printing the result...
String concatenation in Ruby
...;< but that is not the usual way
With string interpolation
source = "#{ROOT_DIR}/#{project}/App.config"
with +
source = "#{ROOT_DIR}/" + project + "/App.config"
The second method seems to be more efficient in term of memory/speed from what I've seen (not measured though). All three methods ...
MySQL “Group By” and “Order By”
... non-aggregate columns in a SELECT with a GROUP BY clause is non-standard. MySQL will generally return the values of the first row it finds and discard the rest. Any ORDER BY clauses will only apply to the returned column value, not to the discarded ones.
IMPORTANT UPDATE
Selecting non-aggregate col...
MYSQL OR vs IN performance
...
Performance reason (quoting MariaDB(a MySQL new free branch) docs): Returns 1 if expr is equal to any of the values in the IN list, else returns 0. If all values are constants, they are evaluated according to the type of expr and sorted. The search for the item t...
How does MySQL process ORDER BY and LIMIT in a query?
... @Green, you're mistaken. Read this for the explanation: dev.mysql.com/doc/refman/5.7/en/limit-optimization.html When the ORDER BY column is indexed, it may return records in a different order than without the LIMIT, when there are more than 1 records with the same value in that column...
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 ...
Get Insert Statement for existing row in MySQL
Using MySQL I can run the query:
15 Answers
15
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ALTER TABLE to add a composite primary key
...r table you will get an error when trying to drop it. In some versions of mysql the error message there was malformed (as of 5.5.17, this error message is still
alter table parent drop column id;
ERROR 1025 (HY000): Error on rename of
'./test/#sql-a04_b' to './test/parent' (errno: 150).
If you ...
NGinx Default public www location?
... have worked with Apache before, so I am aware that the default public web root is typically /var/www/ .
30 Answers
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