I use an update query in mysql to change the published row in my db to 1 or 0. Is there a way to do this automatically in one query, ie, if the database had a 1 in published it would set it to 0 and if it had a 0 it would set it to 1... just like a switch?
Thanks
Assuming the field's a boolean/bit field, then
UPDATE table SET bitfield = ~bitfield
where ~ is mysql's bit-wise NOT operator.
If the field is INT, then:
UPDATE table
SET field = 1 - field
WHERE ...
UPDATE tbl SET published = !published WHERE ...
You can do this with a conditional query. Something like this for example
UPDATE table SET published = IF(published = 1, 0, 1)
Related
I have one field in a table and I'm updating it often; what I want to do is if when that field is updated it equals the same value of another field then update another field.
Let me explain, basically a quicker way of doing this:
UPDATE my_table SET spots_taken=spots_taken+1 WHERE id=1234;
UPDATE my_table SET open=1 WHERE id=1234 AND spots_taken=spots;
Can this be done in one query?
Try using CASE:
UPDATE my_table
SET spots_taken=spots_taken+1,
open = (CASE WHEN spots_taken=spots THEN 1 ELSE open END)
WHERE id=1234
Is it possible to update zero columns in a MySQL update query?
I'd like to utilise the automatic updating of the timestamp column when this particular row is selected. Does anyone have any clue?
So you want your update query to only update the timestamp column? Just update it yourself instead of relying on the automatic update:
UPDATE mytable SET tscolumn = NOW() WHERE ...
Just try something like :
UPDATE myTable SET someField = someField WHERE id = myId
So the data values won't move, and the automatic timestamp will be updated.
As said by GaryG, you may also update the timestamp directly.
How can I make a copy values from one column to another?
I have:
Database name: list
-------------------
number | test
-------------------
123456 | somedata
123486 | somedata1
232344 | 34
I want to have:
Database name: list
----------------
number | test
----------------
123456 | 123456
123486 | 123486
232344 | 232344
What MySQL query should I have?
Short answer for the code in question is:
UPDATE `table` SET test=number
Here table is the table name and it's surrounded by grave accent (aka back-ticks `) as this is MySQL convention to escape keywords (and TABLE is a keyword in that case).
BEWARE!
This is pretty dangerous query which will wipe everything in column test in every row of your table replacing it by the number (regardless of it's value)
It is more common to use WHERE clause to limit your query to only specific set of rows:
UPDATE `products` SET `in_stock` = true WHERE `supplier_id` = 10
UPDATE `table_name` SET `test` = `number`
You can also do any mathematical changes in the process or use MySQL functions to modify the values.
try this:
update `list`
set `test` = `number`
BEWARE : Order of update columns is critical
GOOD: What I want saves existing Value of Status to PrevStatus
UPDATE Collections SET PrevStatus=Status, Status=44 WHERE ID=1487496;
BAD: Status & PrevStatus both end up as 44
UPDATE Collections SET Status=44, PrevStatus=Status WHERE ID=1487496;
try following:
UPDATE `list` SET `test` = `number`
If list is table name and test and number are columns
it creates copy of all values from "number" and paste it to "test"
Following worked for me..
Ensure you are not using Safe-mode in your query editor application. If you are, disable it!
Then run following sql command
for a table say, 'test_update_cmd', source value column col2, target
value column col1 and condition column col3: -
UPDATE test_update_cmd SET col1=col2 WHERE col3='value';
Good Luck!
IF Anyone wants to put Condition
UPDATE bohf SET Sq=IDNo WHERE Table = 'AOF' AND FormSq BETWEEN 13 AND 17
update `table`
set `firstcolumn` = `secondcolumn`
I've got a table with a column, lets call it table_column that is currently null for all rows of the table. I'd like to insert the value "test" into that column for all rows. Can someone give me the SQL for this?
I've tried INSERT INTO table (table_column) VALUES ("test"); but that only populates that last row. How do I do all of the rows at once?
You're looking for UPDATE not insert.
UPDATE mytable
SET table_column = 'test';
UPDATE will change the values of existing rows (and can include a WHERE to make it only affect specific rows), whereas INSERT is adding a new row (which makes it look like it changed only the last row, but in effect is adding a new row with that value).
This is because in relational database terminology, what you want to do is not called "inserting", but "UPDATING" - you are updating an existing row's field from one value (NULL in your case) to "test"
UPDATE your_table SET table_column = "test"
WHERE table_column = NULL
You don't need the second line if you want to update 100% of rows.
To update the content of existing rows use the UPDATE statement:
UPDATE table_name SET table_column = 'test';
What you're actually doing is adding rows. To update the content of existing rows use the UPDATE statement:
UPDATE table SET table_column = 'test';
UPDATE `table` SET table_column='test';
The SQL you need is:
Update table set table_column = "test";
The SQL you posted creates a new row rather than updating existing rows.
To create a new empty column and fill it with the same value (here 100) for every row (in Toad for Oracle):
ALTER TABLE my_table ADD new_column INT;
UPDATE my_table SET new_column = 100;
I want to do all these update in one statement.
update table set ts=ts_1 where id=1
update table set ts=ts_2 where id=2
...
update table set ts=ts_n where id=n
Is it?
Use this:
UPDATE `table` SET `ts`=CONCAT('ts_', `id`);
Yes you can but that would require a table (if only virtual/temporary), where you's store the id + ts value pairs, and then run an UPDATE with the FROM syntax.
Assuming tmpList is a table with an id and a ts_value column, filled with the pairs of id value, ts value you wish to apply.
UPDATE table, tmpList
SET table.ts = tmpList.ts_value
WHERE table.id = tmpList.id
-- AND table.id IN (1, 2, 3, .. n)
-- above "AND" is only needed if somehow you wish to limit it, i.e
-- if tmpTbl has more idsthan you wish to update
A possibly table-less (but similar) approach would involve a CASE statement, as in:
UPDATE table
SET ts = CASE id
WHEN 1 THEN 'ts_1'
WHEN 2 THEN 'ts_2'
-- ..
WHEN n THEN 'ts_n'
END
WHERE id in (1, 2, ... n) -- here this is necessary I believe
Well, without knowing what data, I'm not sure whether the answer is yes or no.
It certainly is possible to update multiple rows at once:
update table table1 set field1='value' where field2='bar'
This will update every row in table2 whose field2 value is 'bar'.
update table1 set field1='value' where field2 in (1, 2, 3, 4)
This will update every row in the table whose field2 value is 1, 2, 3 or 4.
update table1 set field1='value' where field2 > 5
This will update every row in the table whose field2 value is greater than 5.
update table1 set field1=concat('value', id)
This will update every row in the table, setting the field1 value to 'value' plus the value of that row's id field.
You could do it with a case statement, but it wouldn't be pretty:
UPDATE table
SET ts = CASE id WHEN 1 THEN ts_1 WHEN 2 THEN ts_2 ... WHEN n THEN ts_n END
I think that you should expand the context of the problem. Why do you want/need all the updates to be done in one statement? What benefit does that give you? Perhaps there's another way to get that benefit.
Presumably you are interacting with sql via some code, so certainly you can simply make sure that the three updates all happen atomically by creating a function that performs all three of the updates.
e.g. pseudocode:
function update_all_three(val){
// all the updates in one function
}
The difference between a single function update and some kind of update that performs multiple updates at once is probably not a very useful distinction.
generate the statements:
select concat('update table set ts = ts_', id, ' where id = ', id, '; ')
from table
or generate the case conditions, then connect it to your update statement:
select concat('when ', id, ' then ts_', id) from table
You can use INSERT ... ON DUPLICATE KEY UPDATE. See this quesion: Multiple Updates in MySQL
ts_1, ts_2, ts_3, etc. are different fields on the same table? There's no way to do that with a single statement.