Cast varchar that holds some strings to integer field in informix - sql

Question

I have 2 rows from 2 tables in a database that I want to compare.
Column1 is on table1 and is an Integer field with entries like the following
column1
147518
187146
169592
Column2 is on table2 and is a Varchar(15) field with various entries but for this example lets use these 3:
column2
169592
00010000089
DummyId
For my query part of it relies on checking if rows from table1 are linked to the rows in table2, but to do this, I need to compare column1 and column2.
SELECT * FROM table1 WHERE column1 IN (SELECT column2 FROM table2)
The result of this using the data above should be 1 row - 169592
Obviously this wont work (A character to numeric conversion process failed) as they cannot be compared as is, but how do I get them to work?
I have tried
SELECT * FROM table1 WHERE column1 IN (SELECT CAST(column2 AS INTEGER) FROM table2)
and
SELECT * FROM table1 WHERE column1 IN (SELECT (column2::INTEGER) column2 FROM table2)
Using Server Studio 9.1 if that helps.

Answer 1

Try casting the int to a string:
SELECT * FROM table1 WHERE cast(column1 as varchar(15)) IN (SELECT column2 FROM table2)

Answer 2

You can try to use ISNUMERIC in following:
SELECT * FROM table1 WHERE column1 IN (SELECT CASE WHEN ISNUMERIC(column2) = 1 THEN CAST(column2 AS INT) END FROM table2)

Answer 3

For this purpose there is no need to create a special function that you'll not find on other environments.
Let's create a test case for your example:
CREATE TABLE tab1 (
col1 INT,
col2 INT
);
CREATE TABLE tab2 (
col1 VARCHAR(15)
);
INSERT INTO tab1 VALUES(147518,1);
INSERT INTO tab1 VALUES(187146,2);
INSERT INTO tab1 VALUES(169592,3);
INSERT INTO tab2 VALUES(169592);
INSERT INTO tab2 VALUES('00010000089');
INSERT INTO tab2 VALUES('DummyId');
The first query you run was like:
SELECT t1.*
FROM tab1 AS t1
WHERE t1.col1 IN (SELECT t2.col1 FROM tab2 AS t2);
This will raise an error because it tries to compare an INT with a VARCHAR
[infx1210#tardis ~]$ finderr 1213
-1213 A character to numeric conversion process failed.
A character value is being converted to numeric form for storage in a
numeric column or variable. However, the character string cannot be
interpreted as a number. It contains some characters other than white
space, digits, a sign, a decimal, or the letter e; or the parts are in
the wrong order, so the number cannot be deciphered.
If you are using NLS, the decimal character or thousands separator
might be wrong for your locale.
[infx1210#tardis ~]$
Then you've tried to cast a VARCHAR into a INT which resulted in the same error, you should tried the other way:
> SELECT t1.*
> FROM tab1 AS t1
> WHERE t1.col1::CHAR(11) IN (SELECT t2.col1 FROM tab2 AS t2);
>
col1 col2
169592 3
1 row(s) retrieved.
>
Check also if you don't get faster results using the EXISTS:
> SELECT t1.*
> FROM tab1 AS t1
> WHERE EXISTS (
> SELECT 1
> FROM tab2 AS t2
> WHERE t1.col1::CHAR(11) = t2.col1
> );
col1 col2
169592 3
1 row(s) retrieved.
>
Another way possible is to just join the tables:
> SELECT t1.*
> FROM tab1 AS t1
> INNER JOIN tab2 AS t2
> ON (t1.col1 = t2.col1);
col1 col2
169592 3
1 row(s) retrieved.
>

Answer 4

Part of this question was answered by #Stanislovas Kalašnikovas where he said to use the following:
SELECT * FROM table1 WHERE column1 IN (SELECT CASE WHEN ISNUMERIC(column2) = 1 THEN CAST(column2 AS INT) END FROM table2)
But informix does not have a built in function for ISNUMERIC, so the following created it:
create function isnumeric2(inputstr varchar(15)) returning integer;
define numeric_var decimal(15,0);
define function_rtn integer;
on exception in (-1213)
let function_rtn = 0;
end exception with resume
let function_rtn = 1;
let numeric_var = inputstr;
return function_rtn;
end function;
And then the first query above worked for me.