I wanted to know whether i can direct update mysql datas to add (+) the values, without needing to fetch them.
For example:
My database is like this,
data1 = 56
so to add a 4 to it, i will first fetch the data from the database then,
$data1 = $data1 + 4;
and finally again perform a Update query.
So is there is way i can send like add +4 to the current value of data1.
I am using php lanuage.
Thank You
Like... this?
UPDATE
MyTable
SET
Data = Data + 4
WHERE
Myid = 123
A look into basic SQL syntax seems advisable. ;-)
If you are working with PHP to manipulate your data, a deeper look into the mysqli_* functions family in general and prepared/parameterized statements in particular is advisable as well.
mysql_query("UPDATE `mytable` SET `data1` = `data1` + 4");
You'll want a WHERE clause unless you want to update every row.
Related
I'd like to know whether it is possible / advisable (why?), to select data from a table and update the same entry in the same pass
Example
SELECT message_content, message_times_read FROM messages WHERE message_id = 1
Then
UPDATE messages SET message_times_read = message_times_read + 1 WHERE message_id = 1
Can I do them in one call? More importantly, if this is possible, should I? (i.e. is this considered proper practice, is this compatible across different versions, is there performance benefit?)
You must to create a Trigger if you want to do multiples queries in a same query. Check this link if you want to lear more about it: https://www.sitepoint.com/how-to-create-mysql-triggers/
I trying to add +1 in a column after select but its not working, what I want is, when I make a search, the scripts adds +1 in a column to track how much searches I did.
Heres how it is now
$QUERY = "SELECT company FROM test WHERE number = '$number[0]' LIMIT 1";
And I want to add this
UPDATE users SET consultas=consultas+1 WHERE username = '$username'
If I add another $QUERY line the script breaks, any ideas ?
By nature, SELECT queries are for returning information from the database, not updating the database. To this end, triggers aren't even available for SELECT queries to react to the action. As such, if you want to increment a value, this must be done in a separate query, as an UPDATE query or possibly an INSERT ... ON DUPLICATE KEY UPDATE query if that better suits your needs.
You should execute those as two separate queries. Also, be very careful to ensure your data is properly escaped because it looks like you've forgotten to do that.
Be sure to check the result code of each as an error may occur at any time. If you use PDO there's a fairly robust error handling pattern you can follow.
I'm trying to count a table row and add 1 on the outcome, I have this snippet of code.
$countQuery = "SELECT COUNT(id) FROM donations";
$outcomeQuery = mysql_query($countQuery);
$countUp = mysql_fetch_array($outcomeQuery);
$plusOne = 1;
$outcome = $countUp;
echo $outcome[0]
or die(mysql_error());
But this gives me the error:
Fatal error: Unsupported operand types
I need this so I always have a unique number that's not used by a previous donator.
You could use:
SELECT COUNT(id)+1 as IDCount FROM donations
as your query instead. This will save you any mucking about in PHP to do the math. The array you pull back will have the number that you want right off the bat.
Edit: The better alternative however is to use a column type that increments automatically. In MySQL, this is done with the syntax auto_increment in the create table syntax.
Using this, you never actually have to insert a value, but rather, you pass it a NULL as follows (assuming that ID is the field with Auto_increment on it:
insert into tableName (ID,Name) values (null, 'Fluffeh');
So you see you don't give it any values for the ID column - the database takes care of using the right number.
use simple php
$countQuery = mysql_query("SELECT id FROM donations");
$count=mysql_num_rows($countQuery);
$count+=1;
It's dangerous to rely on COUNT to give you a unique number. What happens if two processes execute this query, and then both try and commit: you suddenly have the same value twice.
It would be much safer to implement some kind of sequence function independent of your table contents. This link shows one possibility:
http://forums.mysql.com/read.php?61,143867,238482#msg-238482
This question is for a MySQL database. I suggest you use the AUTO INCREMENT field type.
As you are using PHP, if you need to know the id after inserting a record, use:
mysql_query("INSERT INTO mytable (1, 2, 3, 'blah')");
$id = mysql_insert_id();
See mysql_insert_id().
Using
4 random generated numbers to make 100% sure there are no duplicates
will not make 100% sure there are no duplicates. Don't re-invent the wheel. This is how the problem of ensuring unique incrementing identifiers are used has been solved, you don't need the embarrassment of a homebrew solution that doesn't always work.
I have an array of data that generates unique data on the fly in a manor of speaking. It's actually an array with 5 hashes.
What I want to do is a basic select query with a where clause that checks each via OR basically a one line query rather than a query for each array item.
I'm attempting to ensure that no one hash that enters the db is the same as another which I know the probability is virtually null to that actually happening but it's a possibility none the less, safer than sorry is my perspective on the matter
Anyway the query I'm thinking of makes no sense as if a match is found the query will result in such what I wanna do is from the original array find the one that's not found and use it where if all 5 aren't found I'll just randomly pick one I guess in the end I want to form a result that is 1 to 5 in a new array so I can randomly pick from that result
Is this possible or would it just be easie to cycle over each one with a songle query?
"SELECT
CASE hashes.hash
WHEN $hashes[0] THEN 0
WHEN $hashes[1] THEN 1
WHEN $hashes[2] THEN 2
WHEN $hashes[3] THEN 3
...
END
FROM hashes WHERE hashes.hash IN(".implode($hashes).")"
This should tell you exactly which of the hashes you sent to the server have been found on the server.
The result set would be the index keys (0, 1, 2, 3) of the array that generated the query.
If you sent a query based on an array of 100 hashes and you get a result set of 99 hashes, that means at least one hash was not found in the db.
You could cycle through the result set like this:
while($row = $pdo->fetch()) {
$index = $row[0] // first column of the result set
unset($hashes[$index]);
}
When while finishes the only hashes left in the array should be the ones that weren't found in the database.
My opinion is that it would be easier to to cycle over each one with a single query. From what you say there appears to be no major benefit in doing it all at once.
In that case I would suggest:
alter table myTable create id_bkp int;
update myTable set id_bkp=account_id;
update myTable set account_id=56 where id_bkp=100;
update myTable set account_id=54 where id_bkp=56;
alter table myTable drop id_bkp;
Of course that will depend on what DB system you are using.
Do you mean something like this?
$sql = "SELECT * FROM `table` WHERE `field` = ";
$where_string = "'" . implode("' OR `field` = '",$my_array) . "'";
$sql .= $where_string;
You could use:
$my_array = array_unique($my_array);
To remove duplicate values.
This is what i am doing now : - in PHP
foreach($array as $value)
{
$query = select abc from tblname where colname =" .$value.
// fire query
}
then i create array of these values and display accordingly.
The PROBLEM: -
I have applied foreach, which fires the query every time it encounters a value in the array.
result, if i have 10 values in my array it fires 10 queries. and uses network 10 times, result slow output.
What i want -
I want to give the array to a stored procedure which shall give me a resultset which will have the outputs corresponding to all the elements in the array.
I know this can be done but do not know how.
the mysql doesnot take arrays as datatype.
the result shall be that network shall be used only once, despit of any number of values in the array.
LIKE -
StoredProcedure(inputMysqlARRAY) // not possible, need a workaroung
{
// fire simple select(same) query for each value.
}
then call this stored procedure from PHP and input array. // need workaround.
You just have to be smarter about your calls. For instance, keeping cached DB objects around and that sort of thing.
Without knowing more about your code (your question is fairly garbled), it seems that if your query is something like this:
$query = "select abc from tblname where colname =" .$value; // run 10 times.
You really just need to write smarter code:
$values = array(); // Now, populate this array.
// When you're done, run the query:
$query = 'select abc from tblname where colname IN (\''.implode('\',\'', $values).'\')';
Generally, we refer to this as Dynamic SQL and is the underpinning for how things are typically done today. A stored procedure (or, based on how I read your question, stored function) is useful at times, but is somewhat antiquated as a first-order methodology for interfacing with SQL. The DB guys still sometimes swear by it, but I think that even they are fairly well in consensus that smarter queries are always better.