= is a comparison operator that operates on numbers and strings. Most answers here focus on the wildcard support, which is not the only difference between these operators! You can use the NOT operator to negate the condition provided by the <= operator.LIKE and = are different operators. This time we got only those cities that satisfied both Population <= 100000 OR District = 'Canary Islands' and Name <= 'Ab'. That would give us the same result as the previous query without parentheses.īut look what happens when we move the parentheses to the OR condition. This is like doing the following: SELECT * FROM city We can tell just by looking at this that all cities from the Canary Islands will be returned, plus any cities that satisfy the first criteria. Therefore we got rows that satisfied either Name <= 'Ab' AND Population <= 100000 or District = 'Canary Islands'. In this query, I didn’t provide any parentheses, and so the AND operator was evaluated before the OR operator. | 672 | Santa Cruz de Tenerife | ESP | Canary Islands | 213050 | | 660 | Las Palmas de Gran Canaria | ESP | Canary Islands | 354757 | Parentheses have a higher precedence than all operators, and so you can use parentheses to specify the order in which each condition should be evaluated.Ĭonsider the following example: SELECT * FROM city Furthermore, it evaluates any AND operators before any OR operators. For example, it evaluates any conditional operators before any logical operators, such as AND and OR. Note that SQL has an order of precedence that it assigns to different operator types. You can also use a combination of operators when filtering the results. WHERE Name <= 'Ab' AND Population <= 100000 If you have multiple conditions, you can use multiple <= operators. Basically, it returns all cities that start with letters lower than Ab or exactly Ab. This query returns all cities that are less than or equal to Ab. | 3097 | Aachen | DEU | Nordrhein-Westfalen | 243825 | | 698 | la Laguna | ESP | Canary Islands | 127945 | | 20 | ´s-Hertogenbosch | NLD | Noord-Brabant | 129170 | When comparing with a string value, use quotes around the string literal. You can also use the <= operator to compare string values. Here’s an example to demonstrate using the less than or equal to operator to compare date values. The less than operator doesn’t include the value that you specify. Or we could simply use the less than operator ( <) instead: SELECT * FROM city If we didn’t want this city to be included, we would need to either lower the value: SELECT * FROM city We saw this in the previous example when it included the city with a population of 455, which was the exact value that we specified. The less than or equal to operator includes the specified value in its evaluation. This query returns all cities that have a population of 455 or lower. | 2317 | West Island | CCK | West Island | 167 | | ID | Name | Countr圜ode | District | Population | You can use it to determine whether a value is less than or equal to another value. 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.
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