If we talk at very low-level, cast function converts one column data type into another data-type.
SELECT DEPT_NAME, CAST(DEPT_AMT AS DECIMAL(10,2))
It is very clear from the above example that, DEPT_AMT is a numeric column, then CAST converts it into Decimal(10,2). This is the fundamental use of CAST.
- There are limitations on converting data types.
- With CAST function , You can convert NULL as integer or Char etc.,
- The data conversion CAST (NULL AS INTEGER). This is for single row value.