Once the expression value evaluates and satisfies a condition in the WHEN clause, its corresponding value is returned. In the searched CASE statement, we specify a CASE expression instead of the direct values. For any other values, display Invalid ValueįROM.

If the gender value is F, display it as Female.If the gender value is M, display it as Male.In the below query, we use the following conditions: SQL CASE statements help to standardize the output for defined criteria. Now, our application should display the results without any abbreviations. Suppose we specify the abbreviations for storing employee genders. The standard abbreviations are gender, country codes, marriage status, popular product names, etc. Usually, we use abbreviations to store values in SQL tables. Data standardization using SQL CASE statements We can specify multiple conditions for the CASE statement. For all other values, it displays the output as Inactive EmployeeįROM.If the value in the is 1, then it shows the Active Employee.The following query implements a simple CASE expression. In this type of CASE statement, we use equality check expressions. The SELECT statement with a simple CASE expression You can download its backup from the Microsoft Docs. Note: In this article, we use the Microsoft sample database, AdventureWorks. Let’s explore the SQL CASE statement using various examples.

The CASE statement must end with the END block. It requires at least one set of the WHEN and THEN blocks. For example, if we have a value different then 0 and 1 in the availability column, you get the output from the ELSE code block. If none of the conditions are satisfied, we can use an optional ELSE statement to return the default value. Once a condition evaluates successfully, it stops the evaluation of remaining conditions. SQL Server evaluates the conditions sequentially. Therefore, in the earlier example, the CASE statements work as shown below.Īt a high-level, the syntax for a SQL CASE statement is shown below. In the below image, we see both the database and application perspective.Ī CASE statement in SQL Server evaluates an expression and returns a value based on the defined conditions. Customers just need to view whether the product is available or not. But, from the application perspective, the end-user does not require these values. It is beneficial for the SQL Server query optimizer in preparing the optimized execution plan. If we look at the database perspective, it is a good practice to use the abbreviations or bits wherever possible. Let’s say you store the values for a product’s availability as 1 or 0. Many times, we store the column values in bits 1 or 0. If a voter’s age is greater than 18, they are eligible to vote. If you were looking for logic about voting eligibility, this would be dependent upon the values in the DOB column. For example, suppose you have a voters table with the following details: Mitigate risk with attack path management, threat detection and disaster recoveryĮquip your organization with security solutions that align with Identity Threat Detection and Response (ITDR) protocols.Ī SQL CASE statement evaluates and returns results based on particular values, predicates and conditions as per defined logic.

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Sqlite count with case