To normalize customer data in a staging data extension where a text field named 'birthday' contains date values in various formats, the developer can use the following SQL keywords and functions:
* CASE, ISDATE, CONVERT (A)- These functions can be used to handle different date formats and convert them into a consistent format.
* CASE, ISDATE, CAST (C)- Similar to the above, CAST can be used to convert text to date format if ISDATE returns true.
Example SQL query:
SELECTCASEWHENISDATE(birthday)=1THENCONVERT(DATE,
birthday)ELSENULLENDASnormalized_birthdayFROMStagingDataExtension
References:
* Salesforce Marketing Cloud SQL Reference
* SQL CASE and ISDATE Functions

To execute daily reports on all subscriber activity without impacting send performance, the best practice is tocopy new Send Log records to an Archive data extension, then run reports from the Archive data extension (C). This approach ensures that the reporting activity does not interfere with the performance of ongoing send operations.
References:
* Salesforce Marketing Cloud Send Log Best Practices
* Data Extension Best Practices