Extraer emails distintas tablas sin repetir

[leonardo_josue]

Hola cronosmen:

A qué te refieres con que no puedes hacer un DISTINCT por tabla??? eso es justamente lo que tienes que hacer.

Código MySQL:

mysql> SELECT * FROM tablaA;
+--------------------------+
| mail                     |
+--------------------------+
| [email protected] |
| [email protected] |
| [email protected] |
| [email protected] |
| [email protected] |
+--------------------------+
5 rows in set (0.01 sec)
 
mysql> SELECT * FROM tablaB;
+--------------------------+
| mail                     |
+--------------------------+
| [email protected] |
| [email protected] |
| [email protected] |
+--------------------------+
3 rows in set (0.00 sec)
 
mysql> SELECT * FROM tablaC;
+--------------------------+
| mail                     |
+--------------------------+
| [email protected] |
| [email protected] |
| [email protected] |
| [email protected] |
+--------------------------+
4 rows in set (0.00 sec)
 
mysql> SELECT DISTINCT mail FROM tablaA
    -> UNION
    -> SELECT DISTINCT mail FROM tablaB
    -> UNION
    -> SELECT DISTINCT mail FROM tablaC;
+--------------------------+
| mail                     |
+--------------------------+
| [email protected] |
| [email protected] |
| [email protected] |
| [email protected] |
+--------------------------+
4 rows in set (0.01 sec)
 

El DISTINCT elimina los duplicados en cada tabla, el UNION evita que se repitan registros duplicados... ¿No es esto lo que pretendes obtener?

Saludos
Leo.