Here are some options for deleting duplicate rows from a table in Oracle Database when those rows have a primary key or unique identifier column.
In such cases, the primary key must be ignored when comparing duplicate rows (due to the fact that primary keys hold unique values).
Sometimes you might need to search a database table for only those rows that contain at least one number in a given column.
Technically, numbers can be represented by words and other symbols, but here “number” means “numerical digit”.
Below are examples of how to find rows that contain at least one number in various SQL based DBMSs.
In PostgreSQL, we can use the to_timestamp() function to convert a Unix timestamp value to a date/time value.
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).
Here are four options for returning rows that contain uppercase characters in MariaDB.
Below are two options for returning rows that only contain non-alphanumeric characters in PostgreSQL.
Non-alphanumeric characters include punctuation characters like !@#&()–[{}]:;',?/* and symbols like `~$^+=<>“, as well as whitespace characters like the space or tab characters.
The following SQLite examples return only those rows that have non-numeric values in a given column.
We can use the - operator to subtract one or more weeks from a date in PostgreSQL.
We can use the following technique in PostgreSQL to return the last day of a given month.
This could be the last day of the current month, or the last day of the month based on a date that we specify.
The following PostgreSQL examples return only those rows that don’t have a numeric value in a given column.