Problem with output query sql

[Miguel61]

Hello everyone.

I try this query in the Db MySQL and not receive error:

( SELECT 
A.ESERCIZIO, A.EVENTO, A.DATA, 
A.ORA, A.ORIGINE, A.`DURATA GLOBALE`, 
A.`DESCRIZIONE NODO`, A.LINEA, A.`DESCRIZIONE LINEA`, 
CA.NUMERO, CA.SommaDiNclientiBT, NULL, NULL 
FROM tbl_A A, tbl_CA CA 
WHERE A.LINEA=CA.idLINEA 
AND A.DATA='2008-11-12' 
AND A.ESERCIZIO='DM20' ) 
UNION 
( SELECT A.ESERCIZIO, NULL, A.DATA, 
NULL, NULL, NULL, NULL, 
A.LINEA, NULL, NULL, B.cl_BT, B.cl_MT, NULL 
FROM tbl_A A, tbl_B B 
WHERE B.Cod_linea=A.LINEA 
AND A.DATA='2008-11-12' 
AND A.ESERCIZIO='DM20' ) 
ORDER BY ORA DESC 

But in the output I dont see the value of B.cl_MT... why?

MR

[r937]

because the result set produced by a UNION query uses column names that are taken from the first SELECT

thus, values of B.cl_MT are located in the 12th column, but you have failed to name this column

[Miguel61]

Thanks r937 I understand my error !