Hello I would like to query multiple identical tables in my db which has different prefixes and than display the results randomly but somehow I need to track the origin of the item and I couldn't figure out how
I do the query like this because I don't have access to information_schema
$query = "SHOW TABLES FROM mydb WHERE RIGHT( tables_in_mydb, 5 ) = 'table'";
$res = mysql_query($query);
$num = mysql_num_rows($res);
while($row = mysql_fetch_row($res)) {
$numbers = explode('_', $row[0]);
if($num > 0) {
$q = "SELECT `this`, `that`, `something` FROM ".$numbers[0]."_idetinticaltables"; // :)
$r = mysql_query($q);
while($c = mysql_fetch_array($r)) {
/*display the results randomly with an identifier where the come from*/
}
}
}
You could use ORDER BY RAND() to randomly sort it
The following might work:
Get the list of the tables you're interested in. You already do that.
Create a UNION of multiple SELECT statements. Each SELECT statement differs for the table being selected from and you add a column set to the name of the table (so you can identify it later):
(SELECT *, TABLENAME = 'first_name_of_table' FROM first_name_of_table ...)
UNION
(SELECT *, TABLENAME = 'second_name_of_table' FROM second_name_of_table ...)
UNION
...
ORDER BY RAND() LIMIT 10;
Because it is a UNION you can randomize the whole order then. See How can i optimize MySQL's ORDER BY RAND() function? because it is not that trivial to do well, the example above is only to have an ORDER BY and LIMIT clause placed there. With many entries in your tables, it will kill your server.
$aa=array()
while($c = mysql_fetch_array($r))
{
/*display the results randomly with an identifier where the come from*/
$aa[]=$c;
}
echo $aa; // print "Array"
Related
I'm trying to write a php code to select form tables:
books
images
Some books does not have an image, so I want to skip it and select another book.
I have wrote this code but it does not work with me perfectly.
Now I'm getting only 5 records! it must be 6 as I limited in the book select query.
$slider_sql = "select * from books limit 6";
$slider_result = $conn->query($slider_sql);
while($slider_row = $slider_result->fetch_assoc()) {
extract($slider_row);
$img_sql = "SELECT big_img FROM images WHERE book_id = '$id'";
$img_rs = $conn->query($img_sql);
$img_row = $img_rs->fetch_assoc();
if ($img_rs->num_rows == 0)
continue; //--> here I want to start while again to select another book.
echo $book_name.'<br>';
echo $img_row['big_img'].'<br>';
}
Thanks for your help and time!
Instead of having a sub-query in a loop (which is nearly ALWAYS a bad idea!), use a JOIN instead, which simplifies it to one query instead of two. Then set a condition that big_img should not be empty. This guarantees that you will only find rows where there's an image matching the book. LIMIT will still only ensure the return of 6 rows. <> in MySQL is the same as !=.
$slider_sql = "SELECT b.book_name, i.big_img
FROM books b
JOIN images i
ON i.book_id=b.id
WHERE i.big_img <> ''
LIMIT 6";
$result = $conn->query($slider_sql);
while ($row = $result->fetch_assoc()) {
echo $row['book_name'].'<br>';
echo $row['big_img'].'<br>';
}
MySQL JOIN
Basically, I am seeking to know if there is a better way to accomplish this specific task.
Basically, what happens is I query the db for a list of "project needs" -- These are each uniquer and only appear once.
Then, I search another table to find out how many members have the required "skills - which are directly correlated to the project needs".
I accomplished exactly what I was trying to do by running a second query and then inserting them into an array like this:
function countEachSkill(){
$return = array();
$query = "SELECT DISTINCT SKILL_ID, SKILL_NAME FROM PROJECT_NEEDS";
$result = mysql_query($query) or die(mysql_error());
$num_rows = mysql_num_rows($result);
while($row = mysql_fetch_assoc($result)){
$query = "SELECT COUNT(*) as COUNT FROM MEMBER_SKILLS WHERE SKILL_ID = '".$row['NEED_ID']."'";
$cResult = mysql_query($query);
$cRow = mysql_fetch_assoc($cResult);
$return[$row['SKILL_ID']]['Count'] = $cRow['COUNT'];
$return[$row['SKILL_ID']]['Name'] = $row['SKILL_NAME'];
}
arsort($return);
return $return;
}
But I feel like there has to be a better way (perhaps using some kind of join?) that would return this in a result set to avoid using the array.
Thanks in advance.
PS. I know mysql_ is depreciated. It is not my choice on which to use.
SELECT P.SKILL_ID, P.SKILL_NAME, COUNT(M.SKILL_ID) as COUNT FROM PROJECT_NEEDS P INNER JOIN MEMBER_SKILLS M
ON P.SKILL_ID=M.SKILL_ID
GROUP BY P.SKILL_ID, P.SKILL_NAME
I've adjusted Nriddens answer to accomodate for the select distinct, Im under the belief that his adjustment would be ok given SKILL_ID is a primary key
function countEachSkill(){
$return = array();
$query = "
SELECT
COUNT(*) AS COUNT,
PROJECT_NEEDS.SKILL_NAME,
PROJECT_NEEDS.SKILL_ID
FROM
(SELECT DISTINCT
SKILL_ID, SKILL_NAME
FROM
PROJECT_NEEDS) AS PROJECT_NEEDS
INNER JOIN
MEMBER_SKILLS
ON
MEMBER_SKILLS.SKILL_ID = PROJECT_NEEDS.SKILL_ID
GROUP BY PROJECT_NEEDS.SKILL_ID";
$result = mysql_query($query) or die(mysql_error());
$num_rows = mysql_num_rows($result);
while($row = mysql_fetch_assoc($result)){
$return[$row['SKILL_ID']]['Count'] = $row['COUNT'];
$return[$row['SKILL_ID']]['Name'] = $row['SKILL_NAME'];
}
arsort($return);
return $return;
I am subquerying on the select distinct because I dont believe you have a dedicated skills table with an auto inc primary key, if that was there I wouldn't be using a subquery.
Can you test this query
select project_needs.*,count(members_skills.*) as count from project_needs
inner join members_skills
on members_skills.skill_id=project_needs.skill_id Group by project_needs.skill_name, project_needs.skill_id
I was wondering if someone can help me with my problem that is as follows:
I want to pull once posts.text and uids which belongs to that posts.text but when I execute the code below it does this: eg. there are 4 uids that belongs to the post so I get the posts.text four times instead of once.
$query = mysqli_query($con,
"SELECT posts.text, relationships.uidb
FROM posts
LEFT JOIN relationships
ON posts.uid=relationships.uida
LIMIT 10");
if(mysqli_num_rows($query) > 0){
while($row = mysqli_fetch_assoc($query)){
echo $row['text']." ".$row['uidb']."<br>";
}
}
I would really appreciate any help.
Thanks is advance.
Peter
Update:
Desired output would be like this:
postsArray[0]->text = //post text
postsArray[1]->text = //another post text
postsArray[0]->uids[0] = //approved uid for first post
postsArray[0]->uids[1] = //another approved uid for first post
now it outputs this:
text 10
text 15
text 12
and I want this:
text 10, 15, 12
One way is to use Mysql's GROUP_CONCAT which provides comma separated values list for each group i.e (p.uid)
$query = mysqli_query($con,
"SELECT p.text, GROUP_CONCAT(r.uidb SEPARATOR ', ') uidbs
FROM posts p
LEFT JOIN relationships r
ON p.uid=r.uida
GROUP BY p.uid
LIMIT 10");
if (mysqli_num_rows($query) > 0) {
while ($row = mysqli_fetch_assoc($query)) {
echo $row['text'].' '.$row['uidbs'];
/*$uidbs= explode($row['uidbs'],',');
foreach ($uidbs as $key => $val) {
echo $val.' ';
}*/
echo '</br>';
}
}
GROUP_CONCAT
According to docs The result is truncated to the maximum length that
is given by the group_concat_max_len system variable, which has a
default value of 1024. The value can be set higher, although the
effective maximum length of the return value is constrained by the
value of max_allowed_packet.
Maybe this might work for you:
$query = mysqli_query($con,
"SELECT posts.text, relationships.uidb
FROM posts
LEFT JOIN relationships
ON posts.uid=relationships.uida
GROUP BY posts.uid
LIMIT 10");
if(mysqli_num_rows($query) > 0){
while($row = mysqli_fetch_assoc($query)){
echo $row['text']." ".$row['uidb']."<br>";
}
}
SELECT posts.text, relationships.uidb
FROM posts
LEFT JOIN relationships
ON posts.uid=relationships.uida
GROUP BY posts.primary_key_of_your_post
LIMIT 10
You should call 2 queries. In your first query, call the text, and then call uids.
You should not write complex queries because this will make your business more complex and you will not maintain your code in future.
Faily new to php and mysql, this will probably seem very messy.
This is what I came up with:
$query = "show tables like 'whatever%'";
$result = mysql_query($query);
$num_results = mysql_num_rows($result);
for ($i = 0; $i < $num_results; $i++)
{
$row = mysql_fetch_array($result);
$sql=mysql_query("SELECT * FROM ". $row[0] ." WHERE a=(SELECT MAX(a)) AND b=(SELECT MAX(b)) AND c LIKE 'd%' ORDER BY date DESC LIMIT 1");
while($info=mysql_fetch_array($sql)){
echo "...";
}
}
I get the desired value from each table, so x results depending on the amount of tables. What I would like is to have the results of the queried tables but only show the top 10-5 ordered by date/time.
Is this possible with the current script? Is there an easier way (while, number of tables changing constantly)? Is this query method database intensif?
Cheers!
I call constantly changing number of tables having similar structure a design error. also query switch to
$sql=mysql_query("SELECT * FROM $tbl WHERE c LIKE 'd%' ORDER BY a DESC, b DESC, date DESC LIMIT 1");
is a little relief to database.
The code below works great. I have a MySQL database that contains book titles classified in different categories. In the code below, the variable "site" represents a book title. Each category is represented by a different table in the MySQL database.
The code below ranks the top 25 book titles (site) by total votes across all categories (MySQL tables). I am trying to exclude blank book titles (i. e. when site = ''). How can I do this?
I have tried inserting WHERE site != '' in a few places but I get an error message. So I guess I'm asking, where can I insert WHERE site != ''?
Thanks in advance,
John
<?
mysql_connect("mysqlv10", "username", "password") or die(mysql_error());
mysql_select_db("database") or die(mysql_error());
$result = mysql_query("SHOW TABLES");
$tables = array();
while ($row = mysql_fetch_assoc($result)) {
$tables[] = '`'.$row["Tables_in_bookfeather"].'`';
}
$subQuery = "SELECT site, votes_up FROM ".implode(" UNION ALL SELECT site, votes_up FROM ",$tables);
// Create one query that gets the data you need
$sqlStr = "SELECT site, sum(votes_up) sumVotesUp
FROM (
".$subQuery." ) subQuery
GROUP BY site ORDER BY sum(votes_up) DESC LIMIT 25";
$result = mysql_query($sqlStr);
$arr = array();
echo "<table class=\"samples2\">";
while ($row = mysql_fetch_assoc($result)) {
echo '<tr>';
echo '<td class="sitename2">'.$row["site"].'</td>';
echo '<td>'.$row["sumVotesUp"].'</td>';
echo '</tr>';
}
echo "</table>";
?>
You shouldn't have separate tables for each book category. I can't believe you have so many books that any of these tables would grow too large. Any scalability benefits you might gain by splitting the table are offset by the complexity of having to do these UNION queries.
Here's what I'd do:
Unify the tables into one table.
Add a Categories table.
Relate books to categories with a many-to-many table.
Then your SQL query becomes much simpler:
$sqlStr = "SELECT site, votes_up FROM Books
WHERE site IS NOT NULL AND site <> ''
ORDER BY votes_up DESC LIMIT 25";
It's probably safest to put it in the subquery:
$subQueryParts = array();
foreach($tables as $table)
$subQueryParts[] = "SELECT site, votes_up FROM $table WHERE LENGTH(site)";
$subQuery = implode(" UNION ALL ", $subQueryParts);
If possible, you should follow Bill Karwin's advice and store all your books in one table. Dynamic table names are very hard to search and manage, and they do not optimize well.