LOWER() function is applied to the values in the selected column UPPER() function is applied to the values in the selected column
The use of converting text to lowercase or uppercase in a database query, as demonstrated by the LOWER() and UPPER() functions, serves several purposes:
When comparing or searching for data, it ensures case-insensitive comparisons. For example, if you want to find a customer by name, regardless of whether the input is in uppercase or lowercase, transforming the input and the stored data to a common case (either lowercase or uppercase) ensures accurate and consistent matching.
It helps in presenting data in a consistent format. Displaying names or text in a consistent case format (either all uppercase or all lowercase) can enhance the visual presentation of information in reports or user interfaces.
When ordering or sorting data, transforming the text to a specific case ensures that the sorting is done in a consistent manner. This is especially useful when sorting strings in a case-insensitive manner.
It contributes to data normalization by reducing the potential for duplicate entries due to variations in case. This is important for maintaining data integrity and avoiding issues related to case sensitivity.
It facilitates case-insensitive searches. For instance, when using LIKE or similar search conditions in SQL queries, transforming both the search term and the stored data to a common case ensures that the search is not case-sensitive.
It can be used for data-cleaning purposes. By standardizing the case of text data, you can clean up inconsistencies that might arise from data entry errors or variations.
Using LOWER() and UPPER() functions in SQL queries helps to ensure data consistency, facilitate accurate comparisons, and improve the overall quality and usability of the data in a database.