Catch exit code in bash shell script

The key variable is $?

Example code :

#!/bin/bash

./execute_some_script.sh

if (( $? == 0 ))

then

    echo "the script in script was executed successfully."

else

    echo "the script in script was failed !"

fi

Also a tip for comparing variable as numeric is " if (( $var op $another_var_or_number )) "

String index V.S. Array index in Delphi

I'm used to develop code in C, however someday I meet the need which the code was written in Delphi.

The amazing fact in Delphi is the index on array and string differs ! This is really shock, it shocked me almost put hands in my mouth. 嚇得我吃手手...

In Delphi, Strings are 1-indexed, but arrays are 0-indexed.

也就是說如果有一個變數被設為 String 例如說 S:=Foo.Bar().AsString;
如果要存取 S 的第一個字元要使用 S[1] 才會是正確的字元。

If S is assigned as a string variable, the first character would be S[1] not S[0];

如何找出資料庫中的表格還有建立日期？

很簡單，要去 INFORMATION_SCHEMA 撈資料

SELECT create_time FROM INFORMATION_SCHEMA.TABLES
  WHERE table_schema = '資料庫名稱'
  AND table_name = '表格名稱'

以某次應用，每個月都會新增一張表格，而前端網頁會選擇最近期三筆新增的表格，讓使用者做選擇。這時候下的語法就是

SELECT TABLE_NAME,create_time  FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA="資料庫" \

ORDER BY create_time DESC;

當然這樣的語法撈出來的是所有的 table 但是做完查詢後，不論是用 perl 還是 PHP 就可以撈出來前三筆資料知道是最近三筆新增的 table。