ClickHouse ® Tips #12: Apply Functions to Columns with a Single Call

In ClickHouse®, SELECT modifiers such as APPLY, EXCEPT, and REPLACE enable users to perform simple operations on multiple columns and modify their original values efficiently. The APPLY modifier allows functions to be applied to specified columns, while EXCEPT facilitates the selection of columns excluding those specified. REPLACE enables the application of functions to columns, replacing them with new values through alias expressions. These modifiers can be combined for more complex operations, and future releases, like ClickHouse® 21.10, promise enhancements such as incorporating lambda functions within an APPLY for greater flexibility and functionality.