SQL UPDATE all values in a field with appended string CONCAT not working
SqlMysqlConcatenationConcatSql Problem Overview
Here is what I want to do:
current table:
+----+-------------+
| id | data |
+----+-------------+
| 1 | max |
| 2 | linda |
| 3 | sam |
| 4 | henry |
+----+-------------+
Mystery Query ( something like "UPDATE table SET data = CONCAT(data, 'a')" )
resulting table:
+----+-------------+
| id | data |
+----+-------------+
| 1 | maxa |
| 2 | lindaa |
| 3 | sama |
| 4 | henrya |
+----+-------------+
thats it! I just need to do it in a single query, but can't seem to find a way. I am using mySQL on bluehost (I think its version 4.1)
Thanks everyone.
Sql Solutions
Solution 1 - Sql
That's pretty much all you need:
mysql> select * from t;
+------+-------+
| id | data |
+------+-------+
| 1 | max |
| 2 | linda |
| 3 | sam |
| 4 | henry |
+------+-------+
4 rows in set (0.02 sec)
mysql> update t set data=concat(data, 'a');
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4 Changed: 4 Warnings: 0
mysql> select * from t;
+------+--------+
| id | data |
+------+--------+
| 1 | maxa |
| 2 | lindaa |
| 3 | sama |
| 4 | henrya |
+------+--------+
4 rows in set (0.00 sec)
Not sure why you'd be having trouble, though I am testing this on 5.1.41
Solution 2 - Sql
CONCAT with a null value returns null, so the easiest solution is:
> UPDATE myTable SET spares = IFNULL (CONCAT( spares , "string" ), "string")
Solution 3 - Sql
convert the NULL values with empty string by wrapping it in COALESCE
"UPDATE table SET data = CONCAT(COALESCE(`data`,''), 'a')"
OR
Use CONCAT_WS instead:
"UPDATE table SET data = CONCAT_WS(',',data, 'a')"
Solution 4 - Sql
UPDATE
myTable
SET
col = CONCAT( col , "string" )
Could not work it out. The request syntax was correct, but "0 line affected" when executed.
The solution was :
UPDATE
myTable
SET
col = CONCAT( myTable.col , "string" )
That one worked.
Solution 5 - Sql
UPDATE mytable SET spares = CONCAT(spares, ',', '818') WHERE id = 1
not working for me.
spares is NULL by default but its varchar
Solution 6 - Sql
Solved it. Turns out the column had a limited set of characters it would accept, changed it, and now the query works fine.
Solution 7 - Sql
You can do this:
Update myTable
SET spares = (SELECT CASE WHEN spares IS NULL THEN '' ELSE spares END AS spares WHERE id = 1) + 'some text'
WHERE id = 1
field = field + value does not work when field is null.