Database Management Systems
In MongoDB, the $unionWith aggregation pipeline stage performs a union of two collections, and it includes duplicates.
This behaves in a similar way to SQL’s UNION ALL, which also includes duplicates. By contrast, using just UNION (i.e. without the ALL)in SQL removes duplicates.
In MongoDB, we don’t have the option of specifying $unionWith ALL or similar, so we need to reduce duplicates in another way.
In MongoDB, we can remove duplicates by using the $group stage.
In Oracle, the CONCAT() function performs a string concatenation on its arguments. It returns the string that results from concatenating its arguments.
Concatenation is the operation of joining multiple strings end-to-end.
In Oracle, the WIDTH_BUCKET() function allows you to construct equiwidth histograms, in which the histogram range is divided into intervals that have identical size.
For a given expression, WIDTH_BUCKET() returns the bucket number into which the value of this expression would fall after being evaluated.
Below is a list of the JSON functions available in MariaDB.
In Oracle Database, the TRUNC(number) function returns a given number, truncated to a given number of decimal places.
Oracle also has a TRUNC(date) function, which is used on dates. This article is solely about the TRUNC(number) function, which is used on numbers.
In Oracle, the SIGN() function returns the sign of its argument as -1, 0, or 1, depending on whether the argument is negative, zero, or positive, and also depending on whether the argument is of type NUMBER or a floating-point number.
You can use the SWITCHOFFSET() function in SQL Server to change the time zone offset on a datetimeoffset value.
The function accepts two arguments; a datetimeoffset(n) value (or an expression that can be resolved to a datetimeoffset(n) value), and the new time zone.
In Oracle, the TANH() function returns the hyperbolic tangent of its argument.
In Oracle, the TAN() function returns the tangent of its argument, where the argument is an angle expressed in radians.
If you need to return a small sample of random documents from a collection, here are three approaches you can try using the aggregation pipeline.