DEA-C02 Data Transformation Practice Question
A data engineer needs to transform a string column containing dates in the format 'YYYY-MM-DD' into a DATE type. The column may contain NULL values and occasionally invalid date strings. The engineer wants the transformation to return NULL for invalid strings without causing the query to fail. Which function should the engineer use?
⚠ Common exam trap
The trap here is assuming that TO_DATE or CAST will silently handle invalid dates, when in fact they raise errors and can break the pipeline.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
TRY_TO_DATE
TRY_TO_DATE is specifically designed to return NULL instead of failing when a string cannot be converted to a date. This makes it the correct choice for transforming a column that may contain invalid date strings. TO_DATE and CAST would raise errors, and DATE is not a function. The engineer should use TRY_TO_DATE to ensure the transformation completes successfully.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DATE
Why it's wrong here
DATE is a data type, not a function for converting strings. You cannot call DATE on a string to convert it. This option confuses the type with a function. The correct approach is to use a conversion function that can handle errors, such as TRY_TO_DATE. The DATE keyword is used in declarations, not for runtime conversion.
- ✗
TO_DATE
Why it's wrong here
TO_DATE will raise an error if the string cannot be converted to a date. In a transformation pipeline, this would cause the entire query to fail when encountering invalid data. While it can handle valid strings and NULLs, it does not provide the error tolerance needed for potentially invalid date strings. This option would not meet the requirement.
- ✓
TRY_TO_DATE
Why this is correct
TRY_TO_DATE attempts to convert the string to a date and returns NULL if the conversion fails, rather than raising an error. This is ideal for handling invalid date strings gracefully. It also returns NULL for NULL inputs. The function is designed for exactly this scenario, where data quality is uncertain and you want to avoid query failures.
- ✗
CAST
Why it's wrong here
CAST behaves similarly to TO_DATE and will throw an error for invalid date strings. It does not have a 'try' variant that returns NULL on failure. Using CAST on a column with invalid dates would abort the query. Therefore, it is not suitable for the scenario where invalid strings are expected and should be handled gracefully.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Snowflake exam blueprint
This DEA-C02 practice question is part of Courseiva's free Snowflake certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DEA-C02 exam.