Postgres and Open Source Experts

A "must appear in the GROUP BY clause" error occurs in PostgreSQL when a column is specified in the SELECT statement but it is not utilized in the GROUP BY clause or any aggregate function.

JUSTIFY_INTERVAL() is a built-in DateTime function that utilizes the JUSTIFY_DAYS() and JUSTIFY_HOURS() functions with sign adjustments to adjust the intervals.

In PostgreSQL, a built-in DateTime function named JUSTIFY_HOURS() is used to adjust the 24-hour time periods to days.

In PostgreSQL, the “CLOCK_TIMESTAMP()” function helps us in getting the current DateTime of a database that may change during query execution.

In PostgreSQL, a built-in DateTime function named JUSTIFY_DAYS() is used to adjust the 30-day time periods to months.

In PostgreSQL, the “\d” command and “information_schema.sequences” are used to describe a specific sequence.

In PostgreSQL, the MIN() and MAX() functions can be utilized to retrieve the minimum and maximum values among the list of given values.

To Upgrade PostgreSQL on CentOS 7, add the appropriate repository, stop PostgreSQL, upgrade PostgreSQL, restart PostgreSQL, verify the upgrade, and test the application compatibility.

In PostgreSQL, a commonly faced error “nextval: reached maximum value” error occurs when a sequence reaches its maximum value and the user is still trying to generate a new value.

To query data from a PostgreSQL table, open SQL Shell, and execute the “SELECT *” command followed by the table name.