更改选择查询中的计算字段的类型（sqlite）

Question

im sure i am not the first one to ask this but i can't find the answer to this: I haver a select query on a datatable in a sqlite database.

select *, ((int_EndTime)-(int_StartTime))/60 as dou_usage_min FROM tbl_unautho_usage;

when i run this i get all the fields from the datatable including a new column calculated from to integer columns with unix time stamp values. However, i want my calculated column to be of the type double. With the query above i get a type integer.

select *, ((int_EndTime as float)-(int_StartTime as float))/60 as dou_usage_min FROM tbl_unautho_usage;

Afterwards I tried to change the column type of my integer-columns to float, but this gies me the following error:

near "as": syntax error: 

i got the idea for that from the following post: How to cast computed column with correct decimal/$ result

Answer 1

Try multiplying a value used within the arithmetic operation by 1.0 .

select 
  *, 
  ((int_EndTime*1.0)-(int_StartTime*1.0))/60 as dou_usage_min 
FROM tbl_unautho_usage;

Probably only one value multiplied will be sufficient.

Answer 2

The correct syntax of a CAST expression is "CAST( something AS type )".

But in this case, for the division to be done with floating-point numbers, it is sufficient for at least one of the operands to be a floating-point number:

SELECT *, (int_EndTime - int_StartTime) / 60.0 ...