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  • Database
    • [Day 17] Database Transaction & ACID - (2)
      • Atomicity - each statement in a transaction (to read, write, update or delete data) is treated as a single unit. Either the entire statement is executed, or none of it is executed. This property prevents data loss and corruption from occurring if, for example, if your streaming data source fails mid-stream.
      • Consistency - ensures that transactions only make changes to tables in predefined, predictable ways. Transactional consistency ensures that corruption or errors in your data do not create unintended consequences for the integrity of your table.
      • Isolation - when multiple users are reading and writing from the same table all at once, isolation of their transactions ensures that the concurrent transactions don't interfere with or affect one another. Each request can occur as though they were occurring one by one, even though they're actually occurring simultaneously.
      • Durability - ensures that changes to your data made by successfully executed transactions will be saved, even in the event of system failure.
    • [Day 18] Transaction 併發錯誤與隔離層級 - (1)
      • Dirty Read A dirty read occurs when a transaction reads data that has not yet been committed.
      • Non-repeatable Read A nonrepeatable read occurs when a transaction reads the same row twice but gets different data each time.
      • Phantom Read A phantom is a row that matches the search criteria but is not initially seen.
    • [Day 19] Transaction 併發錯誤與隔離層級 - (2)
      • Read Uncommitted – In this level, one transaction may read not yet committed changes made by other transactions, thereby allowing dirty reads. At this level, transactions are not isolated from each other.
      • Read Committed – This isolation level guarantees that any data read is committed at the moment it is read. Thus it does not allow dirty read. The transaction holds a read or write lock on the current row, and thus prevents other transactions from reading, updating, or deleting it.
      • Repeatable Read – This is the most restrictive isolation level. The transaction holds read locks on all rows it references and writes locks on referenced rows for update and delete actions. Since other transactions cannot read, update or delete these rows, consequently it avoids non-repeatable read.
      • Serizable – This is the highest isolation level. A serializable execution is guaranteed to be serializable. Serializable execution is defined to be an execution of operations in which concurrently executing transactions appears to be serially executing.
  • DBeaver 介面語言
  • What is DBF File Extension? How to Open DBF?
  • Decorator Design Pattern
  • Design Pattern
  • .Net
  • DNS
  • Docker
    • Run CentOS 8 in a docker container 
      $docker pull centos:centos8
$docker run -it --name centos8server centos:centos8 /bin/bash

      $docker exec -it centos8server /bin/bash
    • Container 應用

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Flutter

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DECLARE @t table
(
    Id int,
    Name varchar(10)
)
INSERT INTO @t
SELECT 1,'a' UNION ALL
SELECT 1,'b' UNION ALL
SELECT 2,'c' UNION ALL
SELECT 2,'d' 

SELECT ID,
stuff(
(
    SELECT ','+ [Name] FROM @t WHERE Id = t.Id FOR XML PATH('')
),1,1,'') 
FROM (SELECT DISTINCT ID FROM @t ) t

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nnoremap <space> i<space><esc>

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echo '11@22@33' | xargs -d '@' echo
echo '11@22@33' | tr '@' '\0' | xargs -0 echo  # MacOS

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