To create a Teradata SQL query with a case condition that checks the ID and its starting date, follow these steps:
- Start by writing the basic SQL statement that selects the desired columns from the appropriate tables. For example:
SELECT column1, column2, column3
FROM table1
JOIN table2 ON table1.ID = table2.ID
WHERE ...
- Add a CASE statement to the SELECT clause. This will allow you to evaluate a condition and return different values based on the result. The syntax for a basic CASE statement is:
CASE
WHEN condition THEN value1
WHEN condition THEN value2
ELSE value3
END
- Add the condition to the CASE statement. In this case, you want to check the ID and its starting date, so you'll need to reference those columns in your condition. For example:
CASE
WHEN table1.ID = 12345 AND table1.start_date >= '2021-01-01' THEN 'Active'
ELSE 'Inactive'
END as status
- Incorporate the CASE statement into your overall SQL statement. This might involve using it in a WHERE or HAVING clause, or simply including it as a new column in your SELECT statement. For example:
SELECT column1, column2, column3,
CASE
WHEN table1.ID = 12345 AND table1.start_date >= '2021-01-01' THEN 'Active'
ELSE 'Inactive'
END as status
FROM table1
JOIN table2 ON table1.ID = table2.ID
WHERE ...
- Test and refine your query as needed to ensure it returns the desired results.
