Below are six examples that delete duplicate rows from a table in SQLite when those rows have a primary key or unique identifier column.
In these instances, the primary key must be ignored when comparing duplicates (due to the fact that primary keys prevent duplicate rows by definition).
Continue readingWhen using one of SQLite’s tabular output modes, you can enable the --wrap option in order to limit the width of each column. This can be handy when the data contains long lines of text.
When we do this, we have the option of specifying “word wrap”, so that words don’t get cut off halfway through.
There are two ways to specify word wrap: use --wordwrap on or its shortcut -ww.
The -> and ->> operators were introduced in SQLite version 3.38.0, which was released on 22 February 2022. Both operators are used for extracting subcomponents of JSON. But there’s a subtle difference between them.
If you’re getting “Error: in prepare, SELECTs to the left and right of UNION do not have the same number of result columns…” in when trying to use the UNION operator in SQLite, it’s because one of the SELECT statements is returning more columns than the other.
If you need to calculate the number of seconds that have passed since a given date and time, you can use the UNIXEPOCH() function.
Note that this function was introduced in SQLite 3.38.0, so it will only work if you’re using SQLite 3.38.0 or later.
Continue readingIn SQLite, we can use the DATE() function to add a given number of days to a date.
If we’re dealing with datetime values, we can use the DATETIME() function.
When using the SQLite command line interface (CLI), by default, whenever a query returns a null value, the output is the empty string ('').
We can change this by using the -nullvalue command line option when launching SQLite.
We can also use the .nullvalue dot command if we’re already in the SQLite CLI.
Below is a full list of JSON functions and JSON operators available in SQLite.
Continue readingIn SQLite we can use the upper() function to convert lowercase characters to uppercase.
Here are two methods for returning the Julian Day in SQLite.
The Julian Day is the fractional number of days since noon in Greenwich on November 24, 4714 B.C. It’s the continuous count of days since the beginning of the Julian period, and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.
Continue reading