Database Management Systems
It’s possible to output query results as a JSON document when using the SQLite command line interface.
We can do this with the json output mode.
We can also use SQLite functions like json_object() and/or json_array() to return query results as a JSON document.
In SQLite, substring() is an alias for substr().
It returns a substring from a string, based on a given starting location within the string. Two arguments are required, and a third optional argument is accepted.
The substring() naming was introduced in SQLite 3.34.0, which was released on 1st December 2020. The reason that the substring() syntax was introduced was for compatibility with SQL Server.
SQLite has a number of tabular output modes. One of these is called table mode.
Below is an example of using table mode to output SQLite’s query results as a table.
In PostgreSQL, we can use the + operator to add one or more weeks to a date. We have a few options when it comes to specifying the actual number of weeks.
The SQLite command line interface provides us with several options for outputting our results in tabular format.
These can be set using the .mode command. You simply type .mode followed by the desired output format.
Below are examples of the various tabular modes available in SQLite.
Continue readingThe following examples return only those rows that don’t contain any numeric digits in a given column in Oracle Database.
Continue readingThe unix timestamp is the number of seconds since 1970-01-01 00:00:00 UTC. SQLite provides us with a couple of ways to get the unix timestamp.
Continue readingWhen using PostgreSQL’s INTERSECT operator, if you encounter an error that reads “ERROR: each INTERSECT query must have the same number of columns“, it’s because there’s a mismatch in the number of columns returned by the queries on either side of the INTERSECT operator.
The way to fix this is to ensure that both SELECT statements return the same number of columns.
SQLite has introduced the FORMAT() function, which can be used to format strings.
More precisely, it has actually just renamed its SQL PRINTF() function to FORMAT(). The reason is for better compatibility with other DBMSs. The original PRINTF() name is retained as an alias for backwards compatibility.
The FORMAT() function (or its naming) was introduced in SQLite 3.38.0, which was released on 22 February 2022.
Here are examples of removing duplicate rows from a table in MariaDB when those rows have a primary key or unique identifier column.
The examples delete duplicate rows but keep one. So in the case of two identical rows, it deletes one of them and keeps the other.
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