How can I convert a string to a double precision in PostgreSQL?

Question

How can I convert a string to a double precision in PostgreSQL ?

I tried something like :

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

where latitude is a string and latitude2 is a double. I just can't get it to work.

Answer 1

double is not a postgres data type:

select cast('324342' as double);
ERROR:  type "double" does not exist

but double precision is:

select cast('132342' as double precision);

 float8
--------
 132342
(1 row)

So try:

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