SQL error “ORA-01722: invalid number”

Question

A very easy one for someone, The following insert is giving me the

ORA-01722: invalid number

why?

INSERT INTO C         


        

Answer 1

Well it also can be :

SELECT t.col1, t.col2, ('test' + t.col3) as test_col3 
FROM table t;

where for concatenation in oracle is used the operator || not +.

In this case you get : ORA-01722: invalid number ...