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二进制文件的读写 - App Inventor 2 中文网 - 清泛IT社区，为创新赋能！
app inventor 如何读接收到的二进制文件？读到的二进制文件能否转成列表文件？蓝牙客户端或 ble 都可以接收二进制数组，返回的数据是列表：
如果想要保存二进制到文件，可以考虑转换成 ascii 或 base64 化，然后通过文件管...
WheelView：滚轮选择框扩展 - App Inventor 2 拓展 - 清泛IT社区，为创新赋能！
WheelView, like number picker, but can be any strings.original code from WheelView: 效果类似android4.0以上原生的DatePicker 18Thanks @wildcontrol to sponsor this extensionDemo picture:this demo used 3 extensionsAll the blocks
来源：https://wangsk789.github.io/wheelview/
更多滚轮拓...
How to declare a variable in a PostgreSQL query
...ows you to return a table of temporary values.
WITH master_user AS (
SELECT
login,
registration_date
FROM users
WHERE ...
)
SELECT *
FROM users
WHERE master_login = (SELECT login
FROM master_user)
AND (SELECT registration_date
FROM ma...
Changing selection in a select with the Chosen plugin
I'm trying to change the currently selected option in a select with the Chosen plugin.
4 Answers
...
Create table (structure) from existing table
...
Try:
Select * Into <DestinationTableName> From <SourceTableName> Where 1 = 2
Note that this will not copy indexes, keys, etc.
If you want to copy the entire structure, you need to generate a Create Script of the tab...
Get table names using SELECT statement in MySQL
...
To get the name of all tables use:
SELECT table_name FROM information_schema.tables;
To get the name of the tables from a specific database use:
SELECT table_name FROM information_schema.tables
WHERE table_schema = 'your_database_name';
Now, to answer the...
How to concatenate columns in a Postgres SELECT?
... an explicit coercion to text [...]
Bold emphasis mine. The 2nd example (select a||', '||b from foo) works for any data types since the untyped string literal ', ' defaults to type text making the whole expression valid in any case.
For non-string data types, you can "fix" the 1st statement by c...
Get selected value in dropdown list using JavaScript
How do I get the selected value from a dropdown list using JavaScript?
28 Answers
28
...
default select option as blank
I have a very weird requirement, wherein I am required to have no option selected by default in drop down menu in HTML. However,
...
'IF' in 'SELECT' statement - choose output value based on column values
...
SELECT id,
IF(type = 'P', amount, amount * -1) as amount
FROM report
See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html.
Additionally, you could handle when the condition is null. In the case of...