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.
Continue readingIn 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.
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.
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.
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.
In SQL, the NOT operator negates a Boolean input (it reverses the value of any Boolean expression). Therefore it returns TRUE when the expression is FALSE.
In SQL, the BETWEEN operator allows you to check for values that are within a given range.
The BETWEEN operator specifies a range to test, and it returns TRUE when the operand is within the range of comparisons.
In SQL, the AND operator allows you to check for multiple conditions when filtering your queries.
The AND operator combines two Boolean expressions and returns TRUE when both expressions are TRUE.
In SQL, the OR operator allows you to use alternative conditions when filtering your queries.
The OR operator combines two conditions, and returns TRUE when either of the conditions is TRUE.
In SQL, the EXISTS operator specifies a subquery to test for the existence of rows. It returns TRUE when the subquery returns one or more rows.
A subquery is a query that is nested inside another query (or even another subquery)
This article contains some basic examples of the EXISTS operator.