Hi guys, hope in your help.
I tried this select query and I've this output:
Code:
mysql> SELECT
	A,
	B,
	A * B AS output,
	C
FROM
	tbl_2
ORDER BY
	output DESC;
+-----+---+--------+------+
| A   | B | output | C    |
+-----+---+--------+------+
| 252 | 7 |   1764 | NULL |
| 134 | 7 |    938 | NULL |
| 116 | 6 |    696 | NULL |
| 560 | 1 |    560 | NULL |
| 220 | 2 |    440 | NULL |
| 161 | 2 |    322 | NULL |
| 261 | 1 |    261 | NULL |
| 192 | 1 |    192 | NULL |
| 183 | 1 |    183 | NULL |
| 164 | 1 |    164 | NULL |
| 150 | 1 |    150 | NULL |
| 126 | 1 |    126 | NULL |
|  98 | 1 |     98 | NULL |
|  79 | 1 |     79 | NULL |
|   0 |   |      0 | NULL |
|   0 |   |      0 | NULL |
| 149 | 0 |      0 | NULL |
|   0 |   |      0 | NULL |
+-----+---+--------+------+
18 rows in set
Now I need update the field `C` of tbl_2 with the result of the product (A * B):
Code:
mysql> UPDATE tbl_2
SET C = (
	A * B
);

1292 - Truncated incorrect DOUBLE value: ''
Why this error Truncated incorrect DOUBLE value ?
The field C in the tbl_2 is varchar 255.
Can you help me?
Thank you