SQL and BTEQ have different strengths and weaknesses for ETL tasks. SQL is more portable and flexible, as it can be used with various tools and frameworks, such as Informatica, DataStage, or Talend. It also has more built-in functions and operators for data transformation, such as aggregation, windowing, or string manipulation. However, SQL is not very efficient for complex or iterative logic, as it requires multiple queries or subqueries that may consume more resources and time. BTEQ, on the other hand, is more efficient and powerful for complex or iterative logic, as it can use variables, loops, branches, and error handling to control the flow and execution of the ETL process. It also has some features that are useful for ETL, such as importing and exporting data, generating reports, and logging. However, BTEQ is less portable and flexible, as it is specific to Teradata and may not be compatible with other tools or platforms. It also has fewer built-in functions and operators for data transformation, and may require more coding or customization.