Howard Lee Cloud

軟體工程 Tricky number operation between SQLite and MySQL

By Howard Lee 16 June 2018

Important: The result of 10/110 in SQLite is 0 and different with 0.09090909 when manipulating in MySQL. When testing Laravel Eloquent ORM both at local machine with SQLite and at remote machine with MySQL, you will find some execution results don’t same as expected at local machine. That’s is because SQLite won’t transform integer to real number automatically. Workaround: Add multiply 1.0 to ORM SQL statement and it becomes portable

軟體工程 The quick way to validate you ORM query to SQL

By Howard Lee 13 June 2018

Refer from link: http://laragems.com/post/a-quick-way-to-display-a-sql-query-in-tinker Please enter tinker command: php artisan tinker Type below code: DB::listen(function ($query) { dump($query->sql); dump($query->bindings); dump($query->time); }); And from above line on, every ORM manipulation you type will show what transformed SQL is.

學習 Laravel 5.5 Eloquent relation whereHas and whereRaw usage

By Howard Lee 13 June 2018

Version: Laravel 5.5 Model: Post, Comment Post’s columns: id, title, content, created_at, updated_at Comment’s columns: id, post_id, content, c_date, c_time, u_date, u_time Relation: A post has many comments and a comment belongs to a post. The following shows how to get posts, which had been comments in recent 24 hours. use CarbonCarbon; // use package Post::whereHas('comments', function ($query) { $query->whereRaw('(u_date = ? AND u_time >= ?) OR (u_date =? AND

生活 2018年做了哪些事情

By Howard Lee 07 June 2018

看過長榮航空 2016 和 2017 年財務年報看過 udemy android app 開發課 https://www.udemy.com/master-android-7-nougat-java-app-development-step-by-step/ database 資料庫相關章節的第 166~248 節 . 20180630 補充：已經看完第 249-263 節. 基礎課程的 introduction , downloading and setup, helloworld app, button-counter app. 看完 Youtuber hvass 機器學習

心得調整閱讀文件的順序

By Howard Lee 27 May 2018

日前在選備份 postgres 資料庫的方案選項時，認為應該先看過內建功能的備份和 HA 功能，再考慮要用內建或是外部套件進行，所以細讀一遍 postgres 10.3 的第 26 章和 31 章。預期

軟體工程 Postgres WAL 概述

By Howard Lee 10 May 2018

PostgreSQL version 10 WAL 設定概述參數： checkpoint_timeout default is 5 minute max_wal_size default is 1GB archive_timeout full_page_writes checkpoint_warning checkpoint_completion_target default is 0.5 and only be fraction of checkpoint_timeout pg_test_fsync can measure average speed in microsecond of single WAL flush operation. Half of its value is effective for reporting average time setting that it flush single 8KB write operation to commit_delay. pg_test_fsync doesn’t care whether fsync

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