Google Android Study Jam 學習筆記(6)

1 minute read
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學習範圍

單元 5、單元 6、Jetpack

SQL 語法

  1. statement

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     SELECT name FROM park
 WHERE type != "recreation_area"
 AND area_acres > 100000

  2. function

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    SELECT COUNT(*) FROM park
SELECT SUM(park_visitors) FROM park
SELECT MAX(area_acres) FROM park
SELECT COUNT(DISTINCT type) FROM park

  3. ordering & grouping

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    /* sort by descending order*/
SELECT name FROM park
ORDER BY name DESC
/* see how many parks of each type are present, and get a separate count for each. */
SELECT type, COUNT(*) FROM park
GROUP BY type
ORDER BY type

  4. inserting & deleting

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    INSERT INTO table_name
VALUES (column1, column2, ...)

UPDATE table_name
SET column1 = ...,
column2 = ...,
...
WHERE column_name = ...
...

DELETE FROM table_name
WHERE column_name = ...

Kotlin 語法

  1. companion object: class 中靜態的成員或方法，可以讓 class 不是整個都靜態的

Android Studio

  1. DAO
  2. Flow
  3. datastore
  4. WorkManager
    • Worker
    • WorkRequest
    • WorkManager
  5. Jetpack