operators – Page 20

MongoDB $toBool

January 30, 2021January 29, 2021 by Ian

From MongoDB 4.0, you can use the $toBool aggregation pipeline operator to convert a value to a boolean.

MongoDB $sortByCount Aggregation Operator

March 28, 2021December 30, 2020 by Ian

In MongoDB the $sortByCount aggregation pipeline stage groups incoming documents based on the value of a specified expression, then computes the count of documents in each distinct group.

Each group is output in its own document, which consists of two fields:

an _id field containing the distinct grouping value, and
a count field containing the number of documents belonging to that grouping.

The documents are sorted by count in descending order.

MongoDB $count Aggregation Operator

December 30, 2020 by Ian

In MongoDB the $count aggregation operator passes a document to the next stage in the aggregation pipeline that contains a count of the number of documents input to the current stage.

SQL Greater Than (>) Operator for Beginners

December 3, 2020 by Ian

In SQL, the greater than operator (>) compares two expressions and returns TRUE if the left operand has a value higher than the right operand; otherwise, it returns FALSE.

SQL Greater Than or Equal To (>=) Operator for Beginners

December 3, 2020 by Ian

In SQL, the greater than or equal to operator (>=) compares two expressions and returns TRUE if the left operand has a value greater than or equal to the right operand; otherwise, it returns FALSE.

SQL Less Than or Equal To (<=) Operator for Beginners

December 2, 2020December 2, 2020 by Ian

In SQL, the less than or equal to operator (<=) compares two expressions and returns TRUE if the left operand has a value lower than or equal to the right operand; otherwise, the result is FALSE.

You can use it to determine whether a value is less than or equal to another value.

SQL Less Than (<) Operator for Beginners

December 2, 2020December 2, 2020 by Ian

In SQL, the less than operator (<) compares two expressions and returns TRUE if the left operand has a value lower than the right operand; otherwise, the result is FALSE.

SQL Not Equal To (<>) Operator for Beginners

December 2, 2020 by Ian

In SQL, the not equal to operator (<>) compares the non-equality of two expressions. That is, it tests whether one expression is not equal to another expression.

If either or both operands are NULL, NULL is returned.

SQL also has another not equal to operator (!=), which does the same thing. Which one you use may depend on your DBMS, which one you’re the most comfortable using, and perhaps also whether your organisation has any coding conventions that dictate which one should be used.

SQL Not Equal To (!=) Operator for Beginners

February 11, 2022December 2, 2020 by Ian

In SQL, the not equal to operator (!=) compares the non-equality of two expressions. That is, it tests whether one expression is not equal to another expression.

If either or both operands are NULL, NULL is returned.

SQL also has another not equal to operator (<>), which does the same thing. Which one you use may depend on your DBMS, which one you’re the most comfortable using, and perhaps also whether your organisation has any coding conventions that dictate which one should be used.

SQL Equals (=) Operator for Beginners

December 1, 2020December 1, 2020 by Ian

The equals operator (=) is probably the most commonly used operator in SQL. It compares the equality of two expressions. Even if you’ve only just begun your SQL journey, you’ll probably know this operator.