Greetings,
Read the manuals, please:
(you could look at 5.6 or 5.1 too
accordingly)
mysql> select count(*) from
biblio;
+----------+
| count(*) |
+----------+
| 38497 |
+----------+
1 row in set (0.00 sec)
mysql> select count(*) from biblio where author
is NULL;
+----------+
| count(*) |
+----------+
| 8967 |
+----------+
1 row in set (0.00 sec)
mysql> select
biblio.author,ExtractValue(marcxml,'//datafield[@tag="100"]/subfield[@code>="a"]')
from biblioitems left join biblio on
biblio.biblionumber=biblioitems.biblionumber where biblio.author is
NULL;
+--------+----------------------------------------------------------------------+
| author |
ExtractValue(marcxml,'//datafield[@tag="100"]/subfield[@code>="a"]')
|
+--------+----------------------------------------------------------------------+
| NULL
|
|
| NULL
|
|
...
| NULL
|
|
| NULL
|
|
+--------+----------------------------------------------------------------------+
8967 rows in set (0.89 sec)
mysql> update biblio right join biblioitems on
biblio.biblionumber=biblioitems.biblionumber SET
biblio.author=ExtractValue(biblioitems.marcxml,'//datafield[@tag="100"]/subfield[@code>="a"]')
where biblio.author is NULL;
Query OK, 8967 rows affected (1.68
sec)
Rows matched: 8967 Changed: 8967
Warnings: 0
mysql> select count(*) from biblio where
author is NULL;
+----------+
| count(*) |
+----------+
|
0 |
+----------+
1 row in set (0.00 sec)
Granted, they are all blank still, because
all my records had nothing in the 100$a column for those records.
I don’t know if that will or will not
affect any logic in Koha, as NULL!=space(s). Though you could go back and
replace with NULL for things with no printable characters in it, I’m
sure.
GPML,
Mark
Tompsett