![]() In most of the programming languages, we have the " if" keyword to checkĬonditions. In this article, we will see different ways to check "null safety" in Kotlin. Using other comparison operators returns “Unknown”(NULL).In any programming paradigm, it is mandatory to check "null safety" in order Three-value logic – performing Boolean operations on conditions that involve NULL can either return “Unknown”, “True” or “False”.įor example, using the “IS NULL” keyword when doing comparison operations involving NULL can either return true or false. SELECT * FROM `members` WHERE contact_number IS NULL Įxecuting the above query gives member details whose contact number is NULL membership_ number The employee number should always be supplied The example shown below creates a new table that contains employee’s data. We can use the NOT NULL clause on a given field when creating the table. ![]() Let’s suppose that we want to create a table with certain fields that should always be supplied with values when inserting new rows in a table. In order to avoid such situations from happening, we can employ the use of the NOT NULL clause to limit the results on which our data operates. Performing any arithmetic operations on columns that have the NULL value returns null results. There will be cases when we will have to perform computations on a query result set and return the values. The NOT operator returns false if the condition been tested is true Condition ![]() ![]() The NOT logical operator is used to test for Boolean conditions and returns true if the condition is false. Note: Values that are NULL have not been included SELECT COUNT(contact_number) FROM `members` Įxecuting the above query gives us the following results. ![]()
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