tbl_blood:
id|qty
1 14
2 15
3 16
tbl_blood_list:
id|blood_quantity
1 1
2 1
3 1
My question is the tbl_blood table's column qty should subtract the blood_quantity column in tbl_blood_list's table. I need codes that I can implement in my php mysqli.
I have tried this code but it really cannot work:
$add_inv = "UPDATE tbl_blood
SET qty=(qty - '$blood_quantity')
WHERE id='$minus_blood_id' ";
If i m not misjudging your question so you want to update join but in your table structure i can't find any common column if there is Any common column in both table so you can join and update your table in one statement i think id are common in both table if yes so try this
$pdo->query("UPDATE tbl_blood AS tb JOIN tbl_blood_list AS tbl ON (tbl.id = tb.id) SET tb.qty = (tb.qty - tbl.blood_quantity)")
Please let me know if there is any problem or i misjudge your issue
Hope it's help you.
There are more efficient ways to handle this kind of situation, you should consider a different structure for your program/tables, why having two separate tables when tbl_blood could be decremented directly.
With your current structure, the code below works:
<?php
$pdo = new PDO('mysql:host=localhost;dbname=blood', 'user', 'password');
/* Retrieve values to update */
$result = $pdo->query('
SELECT tb.id, (tb.qty - tbl.blood_quantity) n
FROM tbl_blood tb
LEFT JOIN tbl_blood_list tbl ON (tbl.id = tb.id)');
/* Update */
foreach ($result as $row)
$pdo->query('UPDATE tbl_blood SET qty = '.(int)$row['n'].' WHERE id = '.(int)$row['id'].' LIMIT 1');
?>
Result:
tbl_blood
id|qty
1 13
2 14
3 15
Also:
You may consider harmonizing your field names (e.g. 'blood_qty' and not 'blood_quantity')
Make sure "qty" and "blood_quantity" fields are unsigned integers
Make sure too that both "id" fields are primary keys
You may add a timestamp field in both tables to keep track of updates
Related
I got the two tables(Table1 and Table2):
Table1:
id hits url
1 11 a
2 5 b
3 6 c
4 99 d
5 14 e
Table2:
id url 2014.04.13 2014.04.14
1 a 0 5
2 b 0 1
3 c 0 3
4 d 0 60
5 e 0 10
hi all,
Table1 one contains the actual hits(which are always up-to-date) and Table2 to statistics(which are done every day at midnight). The columns id(unique number) and url are in both tables the same. So they got the same amount of rows.
So i create every day a new column(with the date of today) and copy the column hits from the table 'Table1' into the new created column into the table 'Table2'
First i alter Table2:
$st = $pdo->prepare("ALTER TABLE Table2 ADD `$today_date` INT(4) NOT NULL");
$st->execute();
Then i cache all entries i need from Table1:
$c = 0;
$id = array();
$hits = array();
$sql = "SELECT id, hits FROM Table1 ORDER BY id ASC";
$stmt = $pdo->query($sql);
while($row = $stmt->fetch(PDO::FETCH_ASSOC))
{
$id[$c] = $row['id'];
$hits[$c] = $row['hits'];
$c++;
}
At last i update Table2:
for ($d = 0 ; $d < $c ; $d++)
{
$id_insert = $id[$d];
$sql = "UPDATE DOWNLOADS_TEST SET `$datum_det_dwnloads`=? WHERE id=?";
$q = $pdo->prepare($sql);
$q->execute(array($hits[$d], $id[$d]));
if($q->rowCount() == 1 or $hits[$d] == 0) // success
$hits[$d] = 0;
else // error inserting (e.g. index not found)
$d_error = 1; // error :( //
}
So what i need is to copy(insert) a column from one table to another.
The two tables are having ~2000 elements and the copying as described above takes around 40 sec. The bottleneck is the last part (inserting into the Table2) as i found out.
One thing i found is to do multiple updates in one query. Is there anything i can do besides that?
I hope you realise that at some point your table will have irrational number of columns and will be highly inefficent. I strongly advise you to use other solution, for example another table that holds data for each row for each day.
Let's say you have a table with 2000 rows and two columns: ID and URL. Now you want to know the count of hits for each URL so you add column HITS. But then you realise you will need to know the count of hits for each URL for every date, so your best bet is to split the tables. At this moment you have one table:
Table A (A_ID, URL, HITS)
Now remove HITS from Table A and create Table B with ID and HITS attributes). Now you have:
Table A (A_ID, URL)
Table B (B_ID, HITS)
Next move is to connect those two tables:
Table A (A_ID, URL)
Table B (B_ID, A_ID, HITS)
Where A_ID is foreign key to attribute "A_ID" of Table A. In the end it's the same as first step. But now it's easy to add date attribute to Table B:
Table A (A_ID, URL)
Table B (B_ID, A_ID, HITS, DATE)
And you have your solution for database structure. You will have a lot of entries in table B, but it's still better than a lot of columns. Example of how it would look like:
Table A | A_ID | URL
0 index
1 contact
Table B | B_ID | A_ID | HITS | DATE
0 0 23 12.04.2013
1 1 12 12.04.2013
2 0 219 13.04.2013
3 1 99 13.04.2013
You can also make unique index of A_ID and DATE in Table B, but I prefer to work on IDs even on linking tables.
I have a table that looks like this
id | itemID | catID | Title
----------------------------------------------------------------------------
0 3 4 Hello
1 3 6 Hello
2 4 4 Yo
3 4 8 Yo
4 5 2 Hi
5 1 3 What
I want to do a MySQL PHP Select that only gets one occurrence of the itemID. As you can see they are the same item, just in different categories.
This is what I tried
SELECT * FROM Table GROUP BY itemID
That didn't seem to work, it still just shows duplicates.
Is this what you are looking for? http://www.sqlfiddle.com/#!2/5ba87/1
select itemID, Title from test group by itemID;
As far as MySQL is concerned, the data is all unique, since you want all of the columns. You have to be more specific.
Do you just want the itemID (or other column)? Then say so:
select [column] from Table GROUP BY itemID
Do you want the last entry of a particular item ID? Then say that:
select * from Table where itemID = 1 ORDER BY id DESC
Or the first one?
select * from Table where itemID = 1 ORDER BY id
If none of these are what you want, then you probably need to restructure your tables. It looks like you want different categories for your items. If so, then you'll want to split them out into a new join table, because you have a many-to-many relationship between Items and Categories. I recommend reading up on database normalization, so you're not duplicating data (such as you are with the titles).
If you want everything for the distinct itemIDs, you could certainly take a long route by doing one selection of all of the distinct itemIDs, then doing a series of selections based on the first query's results.
select distinct(`itemID`) from Table
Then in your PHP code, do something like this:
while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
{
$itemID = $row['itemID'];
$sql2 ="SELECT * FROM Table WHERE 1 and `itemID`=\"$itemID\" limit 1";
$result2 = #mysql_query($sql2, $connection);
while ($row2 = mysql_fetch_array($result2))
{
$id = $row2['id'];
$itemID = $row2['itemID'];
$catID = $row2['catID'];
$Title = $row2['Title'];
}
}
I have a Database table in MYSQL, it looks like this:
Project_ID user_ID name
11 1 fred
11 2 rick
11 1 fred
I want to get the names in the table, but when I display it I get the same name twice because the user_ID 1 appears twice in the table. I tried to display it with GROUP BY and SUM, but I don't want to do it this way. How do I get it not to return duplicate rows?
Use DISTINCT
SELECT DISTINCT user_ID
, verschil_ma
FROM project_uren
WHERE project_ID = 11
GROUP BY user_ID
Point 1 is that should the user be assigned to the project twice?
Point 2 - Use the DISTINCT keyword to return only unique records - http://dev.mysql.com/doc/refman/5.0/en/distinct-optimization.html
SELECT DISTINCT user_ID
FROM TABLE
WHERE Project_id = 11
That will return you 1 and 2 (You won't get 1 twice)
Thanks
$results = // query
$results = array_unique($results);
I need help building a SQL query which searches for an user_id (let's say user_id = 5), but this user_id has multiple row entries, but I need to update each row differently though.
I have an array with data which I want to assign to that user_id. Here is a table example:
id user_id amount txn_id
1 5 10 foo_unique
2 5 5 bar_unique
3 7 15 xyz_unique
4 5 10 123_unique
My array would look something like this:
Array (
[0] => 14
[1] => 6
[2] => 9
)
As you see I have three array values and three rows for user_id 5, now I want to add each value of that array, to the corresponding user_id (5). Note that I have an UNIQUE column named txn_id
After updating the table, it would look like this:
id user_id amount txn_id
1 5 14 foo_unique
2 5 5 bar_unique
3 7 6 xyz_unique
4 5 9 123_unique
Any ideas how I could achieve this?
Thanks.
P.S: I cannot use SQL CASE on this issue.
If you want to update one row with a value, you have to be able to have a unique condition for that row.
Without adding some extra field, or condition to uniquely identify a row, you are out of luck.
You can use the following query:
UPDATE MyTable
SET
amount =
CASE id
WHEN 1 THEN 14
WHEN 2 THEN 6
WHEN 3 THEN 9
ELSE amount -- just in case user_id 5 has records not covered above.
END
WHERE
user_id = 5
The problem is, there is nothing on your array that says which array entry belongs to which database row. If you want to rely just on the orders (of the array indices, and the database ids,), you have to SELECT all rows for the user first, then loop and update a row at a time. Something like this on PHP (and PDO):
$values = array(14, 6, 9);
$dbh = new PDO('mysql:host=localhost;dbname=yourdbname', 'username', 'password');
$selectQuery = 'SELECT id FROM yourtable WHERE user_id = 5 ORDER BY id';
foreach($dbh->query($selectQuery) as $row) {
$id = $row['id'];
$sth = $dbh->prepare("UPDATE yourtable SET amount = :val WHERE id = :id");
$sth->execute(array(
'val' => array_unshift($values),
'id' => $id
));
}
(Code above assumes the number of values on your arrays matches the number of database rows for user_id = 5).
Looking at the problem you only need to have SQL statements.
First is to create two tables:
CREATE TABLE users
user_id int(11) PRIMARY KEY NOT NULL,
username varchar(25),
) Engine = InnoDB;
CREATE table userbalances (
balance_id int(11) PRIMARY KEY NOT NULL,
user_id int(11),
amount decimal(10,2),
CONSTRAINT userid_fk FOREIGN KEY userid_fk(user_id) REFERENCES users(userid)
) Engine = InnoDB;
Then, after you have INSERT(ed) all of the users and userbalances inside the table, all you need to do is create an UPDATE statement to update the amount:
UPDATE userbalances SET amount=? WHERE user_id=? AND balanceid=?
The update should be in a loop. And you should use mysql_query() function to update it with the assigned arrays that you have.
Note:
Both userid and balanceid should be in the WHERE clause of your UPDATE statement because you have multiple transactions inside the userbalances table. Otherwise, it's going to change all of the balances of all the transactions of that user.
Problem update:
If you don't use any SQL Cases on this problem, then your problem is just PHP. You need to find out what is the function for UPDATE(ing) - to update the amounts. As long as your tables are all prepopulated. There might be a function on the program you use to update it.
I have a database table. It contains the folowing columns:
Cathegory | Priority |
Is there a finished script or a way to display statistics for these columns?
Basically what I am trying to do is show statistics for these columns.
For example,
cathegory can have different values, as an example: (Continent,
Country, City, Street).
Priority can contain a value between 1-10.
So I would need to display how many rows there are, the and the different values for each row.
For example:
4 of the priority 8 rows have 'continent' as catheogry,
43 of the priority 8 rows have 'country' as cathegory,
329 of the priority 8 rows have 'city' as cathegory
Is this possible?
There are no built-in scripts that can do that for you but certainly you get all that kind of information using SQL, that's the basic idea of a relational database.
Number of rows in table
select count(*) from table;
The example
select cathegory, count(cathegory) nbr_of_cathegories_for_prio_8 from table where priority = 8 group by cathegory;
In you example : 329 of the priority 8 rows have 'city' as cathegory
I assume that:
8 - is the priority value.
329 - how many time the priority is repeated for that specific priority for a specific category.
the PHP implimentation will look something like:
<?php
$sql = "
SELECT Priority, COUNT(Priority) as nbr_of_Priorities, cathegory,
FROM table_Name
GROUP BY Priority, cathegory
";
$result = mysql_query($sql);
while($row = mysql_fetch_array($result))
{
echo $row['nbr_of_Priorities'].'of the priority'.$row[' Priority'];
echo 'has'.$row['cathegory'].'as catheogry';
}
?>