getting error for the below statement in sap datasphere, give me the correct code which should validate in sap datasphere CASE WHEN IS NULL(MNTH_END_STK_VAL_STK) WHERE (CONCAT (MNTH_END_STK_FSCL_YR, MNTH_END_STK_FSCL_MNTH) = (CURRENT_DATE, 'yyyyMM'

The error in your original SQL code stems from incorrect syntax and usage of the `CASE` statement along with the `IS NULL` function. The `WHERE` clause is not valid in a `CASE` statement. Instead, conditions inside a `CASE` statement should be specified using the `WHEN` clause.

Here’s the corrected code that should work in SAP Datasphere:

```sql
CASE 
    WHEN MNTH_END_STK_VAL_STK IS NULL 
         AND CONCAT(MNTH_END_STK_FSCL_YR, LPAD(MNTH_END_STK_FSCL_MNTH, 2, '0')) = TO_VARCHAR(CURRENT_DATE, 'yyyyMM') 
    THEN 0
    ELSE MNTH_END_STK_VAL_STK 
END
```

### Key Adjustments Made:

1. **IS NULL**: The `IS NULL` check is moved into the `WHEN` condition properly.
  
2. **CONCAT() function**: The comparison now combines `MNTH_END_STK_FSCL_YR` and `MNTH_END_STK_FSCL_MNTH`. Note that we ensure monthly values are two digits long with `LPAD`.

3. **TO_VARCHAR**: The `CURRENT_DATE` is appropriately formatted using `TO_VARCHAR(CURRENT_DATE, 'yyyyMM')` to match the string format.

This code snippet now checks if `MNTH_END_STK_VAL_STK` is `NULL` for the specific period defined by `MNTH_END_STK_FSCL_YR` and `MNTH_END_STK_FSCL_MNTH`, returning `0` if true, and the value of `MNTH_END_STK_VAL_STK` otherwise.