# Conditionals Learn how to choose between two values based on a condition. When writing queries, you often need to make decisions or choose between multiple values based on a condition. In CQL, you can use conditionals to express this kind of logic. And as with other expressions, there are two styles you can choose from: one that resembles everyday language and another that is more concise, similar to programming syntax. ## Natural conditionals This style provides a more human-friendly way to express conditionals in CQL. It is similar to how you would write a conditional in English, making the expressions feel more natural. The syntax for expressing conditionals in natural style is as follows: ```cql /**/ if /**/ else /**/ ``` Alternatively, you can use the `otherwise` keyword instead of `else`: ```cql /**/ if /**/ otherwise /**/ ``` You can also omit the `else` or `otherwise` keyword if you do not need an alternate value, in which case the alternate value will be `null`: ```cql /**/ if /**/ ``` Here's an example that conditionally chooses between two strings based on whether the user is new or not: ```cql "Eligible" if user is returning otherwise "Ineligible" ``` Because conditionals are chainable, you can use multiple `else` keywords to add as many cases as you need: ```cql let orders = user's stats' orders; 20% if orders >= 10 else 10% if orders >= 5 otherwise 5% ``` In this example, we map the number of orders to a discount percentage. Frequent customers get 20% off, while customers with fewer orders get 10% or 5% off, depending on the number of orders. To improve clarity, we recommend using parentheses for nested conditionals: ```cql 20% if orders >= 10 else (10% if orders >= 5 else 5%) ``` You can also use line breaks to make the expression more readable: ```cql 20% if orders >= 10 else 10% if orders >= 5 otherwise 5% ``` The above example is especially beneficial for long conditionals, as it improves readability and makes the expression easier to maintain. This allows you to easily add or remove some cases without affecting others. ## Shorthand conditionals The shorthand conditional is a more concise and code-focused way to express conditionals in CQL. It is similar to the ternary operator used in several programming languages, such as JavaScript and Python. The syntax for shorthand conditionals is as follows: ```cql /**/ ? /**/ : /**/ ``` You can also omit the `/**/` to denote you want to use the value of the condition as the consequence: ```cql /**/ ?: /**/ ``` The above example is equivalent to the following: ```cql /**/ ? /**/ : /**/ ``` The following example shows how to use shorthand conditionals to choose between two strings based on whether the user is new or not: ```cql user is new ? "Eligible" : "Ineligible" ``` As with natural conditions, you can chain multiple shorthand conditionals to create more complex expressions: ```cql let orders = user's stats' orders; orders >= 10 ? 20% : (orders >= 5 ? 10% : 5%) ``` When chaining conditionals, it is a good practice to use parentheses for clarity and to avoid [precedence](/reference/cql/expressions/basics#precedence) issues: ```cql orders >= 10 ? 20% : (orders >= 5 ? 10% : 5%) ``` ## Considerations When using conditionals, it is important to remember that the condition must be a boolean value. Otherwise, you will get an evaluation error. Another aspect to consider is that the conditional expression is "greedy", so anything that follows it will be considered part of the alternate branch. For example, consider the following expression: ```cql 90% if user is returning otherwise 10% * price ``` There are two possible interpretations for this expression: either the alternate branch is `10% * price` or the result of the conditional is multiplied by `price`. As the conditional is greedy, the first interpretation is the correct one. To fix this, you can add parentheses around the conditional expression: ```cql (90% if user is returning otherwise 10%) * price ``` The expression now performs the intended task. It first evaluates the conditional expression to determine the discount percentage, then it multiplies the result by the price to get the discounted price.