PostgreSQL has an aggregate function called array_agg() that allows us to generate an array from the result set of a query.
The function accepts an argument which is used to generate the array. This argument is typically the column that we want to use in order to populate the array.
Continue readingIn PostgreSQL we can create arrays with the ARRAY constructor. An array constructor is an expression that builds an array value using values for its member elements.
PostgreSQL has a generate_subscripts() function that generates a series comprising the valid subscripts of a given array.
We pass the array to the function, along with the dimension that we want to use. We also have the option of returning the series in reverse order.
Continue readingIn PostgreSQL array_shuffle() is a system function that randomly shuffles the first dimension of a given array.
The array_shuffle() function was introduced in PostgreSQL 16, which was released on September 14th 2023.
In PostgreSQL array_sample() is a system function that returns an array of a specified number of items randomly selected from the given array.
The array_sample() function was introduced in PostgreSQL 16, which was released on September 14th 2023.
PostgreSQL 16 introduced the date_subtract() function that allows us to subtract an interval from a timestamp with time zone.
It computes times of day and daylight-savings adjustments according to the time zone named by the third argument, or the current TimeZone setting if that is omitted.
PostgreSQL 16 introduced the date_add() function that allows us to add an interval to a timestamp with time zone.
It computes times of day and daylight-savings adjustments according to the time zone named by the third argument, or the current TimeZone setting if that is omitted.
SQLite’s json_valid() function allows us to check whether a JSON string is well formed or not.
Prior to SQLite 3.45.0 the json_valid() function only accepts one argument – the value to check. However, from SQLite 3.45.0 (released on 15 January 2024), we can now provide an optional second argument to define what valid – or “well formed” – means.
When we create a scheduled event in MySQL, the current sql_mode is stored with the event. That causes the event to use the sql_mode that was in effect at the time the event was created. Same with altering an event.
Therefore, if we change the sql_mode after the event was created or altered, it won’t have any impact on the event. In other words, we can safely change our system’s sql_mode without worrying about whether it’s going to mess up any existing scheduled events.
MySQL provides us with the ability to create scheduled events. These are tasks that run according to a specified schedule.
Often referred to simply as events, scheduled events can be created with the CREATE EVENT statement, they can be modified with the ALTER EVENT statement, and they can be removed with the DROP EVENT statement.