The following example deletes duplicate rows in MySQL while ignoring the primary key or unique identifier column.
The example deletes duplicate rows but keeps one. So in the case of two identical rows, it deletes one of them and keeps the other.
Continue readingIn SQL Server, we can use the following method to return a date and time based on a given Unix timestamp.
The Unix timestamp (also known as Unix Epoch time, Unix time, or POSIX time) is the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970, Coordinated Universal Time (UTC).
Continue readingIn PostgreSQL, we can use the extract() function along with the epoch argument to return the Unix timestamp.
We can return the Unix timestamp based on the current date/time, or we can get it based on another specified date/time.
Continue readingHere are a couple of ways to return the number of days in a given month in Oracle Database. This could be the number of days in the current month, or the number of days in a month based on a specified date.
Continue readingBelow are two methods for returning rows that contain only non-alphanumeric characters in MariaDB.
Non-alphanumeric characters include punctuation characters like !@#&()–[{}]:;',?/* and symbols like `~$^+=<>“, as well as whitespace characters like the space or tab characters.
In SQLite, we can use the DATE() function to subtract one or more days from a date.
For datetime values, we can use the DATETIME() function.
Here’s a nifty trick we can use in MariaDB to return the number of days in a month based on a given date.
Continue readingIf you encounter an error that reads “INSERT has more expressions than target columns” when trying to insert data in Postgres, it’s because you’re trying to insert data into more columns than the table actually contains.
Continue readingBelow are three options for using T-SQL to return the first day of the month in SQL Server.
This could be the first day of the current month, or the first day of a month based on a given date.
Continue readingIn PostgreSQL, we can use the - operator to subtract one or more minutes from a time value.
By “time” value, this could be an actual time value, a timestamp, or an interval. We can also subtract minutes from a date value or a date and time combination.