How can I convert a string to a double precision in PostgreSQL?
double is not a postgres data type:




select cast('324342' as double);



ERROR:  type &quot;double&quot; does not exist
LINE 1: select cast('324342' as double);
                                ^



but double precision is:




select cast('132342' as double precision);



| float8 |
| :----- |
| 132342 |



So try:

update points set latitude2 = cast(latitude as double precision) ;


if you prefer, you can use float * instead, because according to the docs:


  float with no precision specified is taken to mean double precision





select cast('132342' as float);



| float8 |
| :----- |
| 132342 |



db&lt;>fiddle here



* or float(n) where 25&lt;=n&lt;=53 because that is also taken to mean double precision