Does case statement work in bigquery sandbox?

Question

I'm getting this error when I tried to run the query:

No matching signature for operator CASE; all THEN/ELSE arguments must be coercible to a common type but found: BOOL, STRING; actual argument types (WHEN THEN) ELSE: (BOOL BOOL) STRING at [3:2]

**Query **

SELECT  
 customer_id,
 CASE 
  WHEN name = 'Devadas Sloan' THEN name = 'Devdas Sloan'
  ELSE name
  END AS new_name
FROM `valid-cell-380712.customer_table_gda.customer_table` 

Answer 1

You are trying to do an assignment inside the CASE statement, when all you need is to generate an if and else value. Use this version:

SELECT
    customer_id,
    CASE WHEN name = 'Devadas Sloan' THEN name ELSE name END AS new_name
FROM valid-cell-380712.customer_table_gda.customer_table;

Of course, the above CASE expression just returns name in all cases. It would make more sense if you wanted to replace Devadas Sloan with some other name, e.g. use:

SELECT
    customer_id,
    CASE WHEN name = 'Devadas Sloan' THEN 'D Sloan' ELSE name END AS new_name
FROM valid-cell-380712.customer_table_gda.customer_table;