Question

My data set contains separate year, month, day, hour, minute, and second columns as following that are separated by space:

+-------------------+
|2007|09|28|21|14|06|
|2007|09|28|21|14|06|
|2007|09|28|21|14|06|
|2007|09|28|21|14|06|
|2007|09|28|21|14|06|
+-------------------+

I wanted to integrate them as a single column under timestamp data-type.
I have created a new column in timestamp data-type and update the column by following code:

 Update s2
 set dt = year || '-' || month  || '-' || day
               || ' ' || hour  || ':' || min  || ':' || second 

But I faced by following error:

ERROR:  column "dt" is of type timestamp without time zone but expression is of type text
LINE 1:  Update temp set dt= year || '-' || month  || '-' || day  ||...
                             ^
HINT:  You will need to rewrite or cast the expression.

********** Error **********

ERROR: column "dt" is of type timestamp without time zone but expression is of type text
SQL state: 42804
Hint: You will need to rewrite or cast the expression.
Character: 22

Moreover, I can preform the integration by varchar data-type.

Answer 1

The result of the expression

year || '-' || month  || '-' || day || ' ' || hour  || ':' || min  || ':' || second 

is not a timestamp but a plain text. The error message simply tells you, that the type text is not appropriate to the type of the dt column.

You must cast the complete expression like this:

(year || '-' || month  || '-' || day || ' ' || hour  || ':' || min  || ':' || second)::timestamp