Category Archives: Database

MSSQL – Select rows which are created within a specific period

Assume the table has a column called CREATED_DATE which stores the creation date. The following SQL make use of the DATEADD() function to select records which are created within the recent 10 days.

  CREATED_DATE > DATEADD(day, -10, getdate())


We can use different unit in the datepart (The first argument in DATEADD()) as stated in the 2nd reference link below.

Done =)


OS X – Fail to start MySQL server which is installed by Homebrew

After i reboot my OS X, i find that i couldn’t start the MySQL server and it throws the following error:

hatuey:5.6.19 yingkityuen$ mysql.server start
Starting MySQL
. ERROR! The server quit without updating PID file (/usr/local/var/mysql/


Go to the above folder and delete the mysql error log which is ended with .err. In my case, i executed the following command:

hatuey:5.6.19 yingkityuen$ rm /usr/local/var/mysql/hatuey.local.err

Where hatuey is my Mac machine name.

This should fix the problem.

Done =)

Reference: Mahdi Yusuf – MySQL ‘The server quit without updating PID file’

PostgreSQL – Set and Get Timezone

There is a timezone configuration on PostgreSQL server. If you want to change the default globally, you can edit the postgresql.conf. On Ubuntu, it is located at

  • /etc/postgresql/<version>/main/postgresql.conf
# - Locale and Formatting -

datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
#timezone = 'Hongkong'
timezone = 'UTC'


We could also tweak the timezone only in your current PostgreSQL session.

1. Get the current timezone.

SELECT current_setting('TIMEZONE');

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