I have two tables properties and buildings. I want to extract rows from the buildings table according to a criteria.
I have put these buildings ids in a variable, as below:
$buildings = "1,2,3,4,5,6,7,8,9,10"
I am trying to access the properties according to the above list.
SELECT * FROM properties WHERE BUILDING_ID IN ('{$buildings}')
but I am not getting the desired result. How can I get the desired result? Is this the right approach?
Remove the single quotes (and optionally the braces).
$query = "SELECT * FROM properties WHERE BUILDING_ID IN ($buildings)"
Note that IN is not always the most efficient as it can't use indexes - if you can use BETWEEN instead, you may get better performance on a large dataset. But for smaller datasets, IN is fine.
You could do something like:
$buildings = "1,2,3,4,5,6,7,8,9,10";
$buildingIDs = explode(",", $buildings);
$buildingQueries = array();
foreach ($buildingIDs as $buildingID) {
$buildingQueries[] = "BUILDING_ID = " . $buildingID;
}
$query = "SELECT * FROM properties WHERE " . implode(" OR ", $buildingQueries);
That will let you take advantage of indexes, and allow for variable IDs.
Warning: you should look into mysqli or PDO, and move away from the soon to be deprecated mysql library
Related
For an application I'm trying to count the total of friends. I want to do this with a function but it isn't returning anything. It tells me this:
Warning: mysqli_query() expects at least 2 parameters, 1 given
But I only need one parameter. I think I'm totally wrong.
This is the function:
public function GetTotalOfFriends($user_id){
$db = new Db();
$select = "SELECT COUNT FROM friendship WHERE (friendship_recipient_id ='" . $user_id ."' OR friendship_applicant_id = '" . $user_id . "') AND friendship_status = 'accepted'";
$result = $db->conn->query($select);
$row = mysqli_query($result);
$total = $row[0];
echo $total;
I'm trying to print it out in this way:
$friend = new Friendship;
$numberoffriends = $friend->GetTotalOfFriends($user_id);
<?php echo $numberoffriends; ?>
You are mixing up a couple of things. The line $result = $db->conn->query($select); already seems to execute a query, but then you try to bypass your database wrapper by passing that query result again to mysqli_query.
Apart from that, I think your query itself is also wrong. COUNT needs a parameter, indicating a field or value to count. Quite often COUNT(*) is used, but COUNT('x') might be more efficient in some cases. You can also use a specific field name, and COUNT will count the non-null values for you.
The result you got is a mysql_result object, which you need to use to get to the actual data of the query result.
The documentation of this object is here and I suggest that you read it thoroughly.
One possible way to do this is using this:
$resultArray = $result->fetch_row();
This will result in the first (and only) row of your query. It is represented as an array, with one value (since your query returns only one column). You can fetch that value like this:
return $resultArray[0];
You could also use any of the other fetch methods if you want your data in a different fashion.
I have a question on how to go about the next phase of a project I am working on.
Phase I:
create a php script that scraped directory for all .txt file..
Open/parse each line, explode into array...
Loop through array picking out pieces of data that were needed and INSERTING everything into the database (120+ .txt files & 100k records inserted)..
this leads me to my next step,
Phase II:
I need to take a 'list' of several 10's of thousand of numbers..
loop through each one, using that piece of data (number) as the search term to QUERY the database.. if a match is found I need to grab a piece of data in a different column of the same record/row..
General thoughts/steps I plan to take
scrape directory to find 'source' text file.
open/parse 'source file'.... line by line...
explode each line by its delimiting character.. and grab the 'target search number'
dump each number into a 'master list' array...
loop through my 'master list' array.. using each number in my search (SELECT) statement..
if a match is found, grab a piece of data in another column in the matching/returned row (record)...
output this data.. either to screen or .txt file (havent decided on that step yet,..most likely text file through each returned number on a new line)
Specifics:
I am not sure how to go about doing a 'multiple' search/select statement like this?
How can I do multiple SELECT statements each with a unique search term? and also collect the returned column data?
is the DB fast enough to return the matching value/data in a loop like this? Do I need to wait/pause/delay somehow for the return data before iterating through the loop again?
thanks!
current function I am using/trying:
this is where I am currently:
$harNumArray2 = implode(',', $harNumArray);
//$harNumArray2 = '"' . implode('","', $harNumArray) . '"';
$query = "SELECT guar_nu FROM placements WHERE har_id IN ($harNumArray2)";
echo $query;
$match = mysql_query($query);
//$match = mysql_query('"' . $query . '"');
$results = $match;
echo("<BR><BR>");
print_r($results);
I get these outputs respectively:
Array ( [0] => sample_source.txt )
Total FILES TO GRAB HAR ID's FROM: 1
TOAL HARS FOUND IN ALL FILES: 5
SELECT guar_nu FROM placements WHERE har_id IN ("108383442","106620416","109570835","109700427","100022236")
&
Array ( [0] => sample_source.txt )
Total FILES TO GRAB HAR ID's FROM: 1
TOAL HARS FOUND IN ALL FILES: 5
SELECT guar_nu FROM placements WHERE har_id IN (108383442,106620416,109570835,109700427,100022236)
Where do I stick this to actually execute it now?
thanks!
update:
this code seems to be working 'ok'.. but I dont understand on how to handle the retirned data correctly.. I seem to only be outputting (printing) the last variable/rows data..instead of the entire list..
$harNumArray2 = implode(',', $harNumArray);
//$harNumArray2 = '"' . implode('","', $harNumArray) . '"';
//$query = "'SELECT guar_num FROM placements WHERE har_id IN ($harNumArray2)'";
$result = mysql_query("SELECT har_id, guar_num FROM placements WHERE har_id IN (" . $harNumArray2 . ")")
//$result = mysql_query("SELECT har_id, guar_num FROM placements WHERE har_id IN (0108383442,0106620416)")
or die(mysql_error());
// store the record of the "example" table into $row
$row = mysql_fetch_array($result);
$numRows = mysql_num_rows($result);
/*
while($row = #mysql_fetch_assoc($result) ){
// do something
echo("something <BR>");
}
*/
// Print out the contents of the entry
echo("TOTAL ROWS RETURNED : " . $numRows . "<BR>");
echo "HAR ID: ".$row['har_id'];
echo " GUAR ID: ".$row['guar_num'];
How do I handle this returned data properly?
thanks!
I don't know if this answers your question but I think you're asking about sub-queries. They're pretty straightforward and just look something like this
SELECT * FROM tbl1 WHERE id = (SELECT num FROM tbl2 WHERE id = 1);
That will only work if there is one unique value to that second subquery. If it returns multiple rows it will return a parse error. If you have to select multiple rows research JOIN statements. This can get you started
http://www.w3schools.com/sql/sql_join.asp
I am not sure how to go about doing a 'multiple' search/select statement like this?
With regards to a multiple select, (and I'll assume that you're using MySQL) you can perform that simply with the "IN" keyword:
for example:
SELECT *
FROM YOUR_TABLE
WHERE COLUMN_NAME IN (LIST, OF, SEARCH, VALUES, SEPARATED, BY COMMAS)
EDIT: following your updated code in the question.
just a point before we go on... you should try to avoid the mysql_ functions in PHP for new code, as they are about to be deprecated. Think about using the generic PHP DB handler PDO or the newer mysqli_ functions. More help on choosing the "right" API for you is here.
How do I handle this returned data properly?
For handling more than one row of data (which you are), you should use a loop. Something like the following should do it (and my example will use the mysqli_ functions - which are probably a little more similar to the API you've been using):
$mysqli = mysqli_connect("localhost", "user", "pass");
mysqli_select_db($mysqli, "YOUR_DB");
// make a comma separated list of the $ids.
$ids = join(", ", $id_list);
// note: you need to pass the db connection to many of these methods with the mysqli_ API
$results = mysqli_query($mysqli, "SELECT har_id, guar_num FROM placements WHERE har_id IN ($ids)");
$num_rows = mysqli_num_rows($results);
while ($row = mysqli_fetch_assoc($results)) {
echo "HAR_ID: ". $row["har_id"]. "\tGUAR_NUM: " . $row["guar_num"] . "\n";
}
Please be aware that this is very basic (and untested!) code, just to show the bare minimum of the steps. :)
I have a sql query that is generated using php. It returns the surrogate key of any record that has fields matching the search term as well as any record that has related records in other tables matching the search term.
I join the tables into one then use a separate function to retrieve a list of the columns contained in the tables (I want to allow additions to tables without re-writing php code to lower ongoing maintenance).
Then use this code
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$qry_string.="UPPER(";
$qry_string.=$cur_col;
$qry_string.=") like '%";
$qry_string.=strtoupper($term_searching);
$qry_string.="%' or ";
}
}
To generate the rest of the query string
select tbl_sub_model.sub_model_sk from tbl_sub_model inner join [about 10 other tables]
where [much code removed] or UPPER(tbl_model.image_id) like '%HONDA%' or
UPPER(tbl_model.image_id) like '%ACCORD%' or UPPER(tbl_badge.sub_model_sk) like '%HONDA%'
or UPPER(tbl_badge.sub_model_sk) like '%ACCORD%' or UPPER(tbl_badge.badge) like '%HONDA%'
or UPPER(tbl_badge.badge) like '%ACCORD%' group by tbl_sub_model.sub_model_sk
It does what I want it to do however it is vulnerable to sql injection. I have been replacing my mysql_* code with pdo to prevent that but how I'm going to secure this one is beyond me.
So my question is, how do I search all these tables in a secure fashion?
Here is a solution that asks the database to uppercase the search terms and also to adorn them with '%' wildcards:
$parameters = array();
$conditions = array();
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$conditions[] = "UPPER( $cur_col ) LIKE CONCAT('%', UPPER(?), '%')";
$parameters[] = $term_searching;
}
}
$STH = $DBH->prepare('SELECT fields FROM tbl WHERE ' . implode(' OR ', $conditions));
$STH->execute($parameters);
Notes:
We let MySQL call UPPER() on the user's search term, rather than having PHP call strtoupper()
That should limit possible hilarious/confounding mismatched character set issues. All your normalization happens in one place, and as close as possible to the moment of use.
CONCAT() is MySQL-specific
However, as you tagged the question [mysql], that's probably not an issue.
This query, like your original query, will defy indexing.
Try something like this using an array to hold parameters. Notice % is added before and after term as LIKE %?% does not work in query string.PHP Manual
//Create array to hold $term_searching
$data = array();
foreach ($col_array as $cur_col) {
foreach ($search_terms_array as $term_searching) {
$item = "%".strtoupper($term_searching)."%";//LIKE %?% does not work
array_push($data,$item)
$qry_string.="UPPER(";
$qry_string.=$cur_col;
$qry_string.=") LIKE ? OR";
}
}
$qry_string = substr($qry_string, 0, -3);//Added to remove last OR
$STH = $DBH->prepare("SELECT fields FROM table WHERE ". $qry_string);//prepare added
$STH->execute($data);
EDIT
$qry_string = substr($qry_string, 0, -3) added to remove last occurrence of OR and prepare added to $STH = $DBH->prepare("SElECT fields FROM table WHERE". $qry_string)
I am trying to figure out a script to take a MySQL query and turn it into individual queries, i.e. denormalizing the query dynamically.
As a test I have built a simple article system that has 4 tables:
articles
article_id
article_format_id
article_title
article_body
article_date
article_categories
article_id
category_id
categories
category_id
category_title
formats
format_id
format_title
An article can be in more than one category but only have one format. I feel this is a good example of a real-life situation.
On the category page which lists all of the articles (pulling in the format_title as well) this could be easily achieved with the following query:
SELECT articles.*, formats.format_title
FROM articles
INNER JOIN formats ON articles.article_format_id = formats.format_id
INNER JOIN article_categories ON articles.article_id = article_categories.article_id
WHERE article_categories.category_id = 2
ORDER BY articles.article_date DESC
However the script I am trying to build would receive this query, parse it and run the queries individually.
So in this category page example the script would effectively run this (worked out dynamically):
// Select article_categories
$sql = "SELECT * FROM article_categories WHERE category_id = 2";
$query = mysql_query($sql);
while ($row_article_categories = mysql_fetch_array($query, MYSQL_ASSOC)) {
// Select articles
$sql2 = "SELECT * FROM articles WHERE article_id = " . $row_article_categories['article_id'];
$query2 = mysql_query($sql2);
while ($row_articles = mysql_fetch_array($query2, MYSQL_ASSOC)) {
// Select formats
$sql3 = "SELECT * FROM formats WHERE format_id = " . $row_articles['article_format_id'];
$query3 = mysql_query($sql3);
$row_formats = mysql_fetch_array($query3, MYSQL_ASSOC);
// Merge articles and formats
$row_articles = array_merge($row_articles, $row_formats);
// Add to array
$out[] = $row_articles;
}
}
// Sort articles by date
foreach ($out as $key => $row) {
$arr[$key] = $row['article_date'];
}
array_multisort($arr, SORT_DESC, $out);
// Output articles - this would not be part of the script obviously it should just return the $out array
foreach ($out as $row) {
echo '<p>'.$row['article_title'].' <i>('.$row['format_title'].')</i><br />'.$row['article_body'].'<br /><span class="date">'.date("F jS Y", strtotime($row['article_date'])).'</span></p>';
}
The challenges of this are working out the correct queries in the right order, as you can put column names for SELECT and JOIN's in any order in the query (this is what MySQL and other SQL databases translate so well) and working out the information logic in PHP.
I am currently parsing the query using SQL_Parser which works well in splitting up the query into a multi-dimensional array, but working out the stuff mentioned above is the headache.
Any help or suggestions would be much appreciated.
From what I gather you're trying to put a layer between a 3rd-party forum application that you can't modify (obfuscated code perhaps?) and MySQL. This layer will intercept queries, re-write them to be executable individually, and generate PHP code to execute them against the database and return the aggregate result. This is a very bad idea.
It seems strange that you imply the impossibility of adding code and simultaneously suggest generating code to be added. Hopefully you're not planning on using something like funcall to inject code. This is a very bad idea.
The calls from others to avoid your initial approach and focus on the database is very sound advice. I'll add my voice to that hopefully growing chorus.
We'll assume some constraints:
You're running MySQL 5.0 or greater.
The queries cannot change.
The database tables cannot be changed.
You already have appropriate indexes in place for the tables the troublesome queries are referencing.
You have triple-checked the slow queries (and run EXPLAIN) hitting your DB and have attempted to setup indexes that would help them run faster.
The load the inner joins are placing on your MySQL install is unacceptable.
Three possible solutions:
You could deal with this problem easily by investing money into your current database by upgrading the hardware it runs on to something with more cores, more (as much as you can afford) RAM, and faster disks. If you've got the money Fusion-io's products come highly recommended for this sort of thing. This is probably the simpler of the three options I'll offer
Setup a second master MySQL database and pair it with the first. Make sure you have the ability to force AUTO_INCREMENT id alternation (one DB uses even id's, the other odd). This doesn't scale forever, but it does offer you some breathing room for the price of the hardware and rack space. Again, beef up the hardware. You may have already done this, but if not it's worth consideration.
Use something like dbShards. You still need to throw more hardware at this, but you have the added benefit of being able to scale beyond two machines and you can buy lower cost hardware over time.
To improve database performance you typically look for ways to:
Reduce the number of database calls
Making each database call as efficient as possible (via good design)
Reduce the amount of data to be transfered
...and you are doing the exact opposite? Deliberately?
On what grounds?
I'm sorry, you are doing this entirely wrong, and every single problem you encounter down this road will all be consequences of that first decision to implement a database engine outside of the database engine. You will be forced to work around work-arounds all the way to delivery date. (if you get there).
Also, we are talking about a forum? I mean, come on! Even on the most "web-scale-awesome-sauce" forums we're talking about less than what, 100 tps on average? You could do that on your laptop!
My advice is to forget about all this and implement things the most simple possible way. Then cache the aggregates (most recent, popular, statistics, whatever) in the application layer. Everything else in a forum is already primary key lookups.
I agree it sounds like a bad choice, but I can think of some situations where splitting a query could be useful.
I would try something similar to this, relying heavily on regular expressions for parsing the query. It would work in a very limited of cases, but it's support could be expanded progressively when needed.
<?php
/**
* That's a weird problem, but an interesting challenge!
* #link http://stackoverflow.com/questions/5019467/problem-writing-a-mysql-parser-to-split-joins-and-run-them-as-individual-query
*/
// Taken from the given example:
$sql = "SELECT articles.*, formats.format_title
FROM articles
INNER JOIN formats ON articles.article_format_id = formats.format_id
INNER JOIN article_categories ON articles.article_id = article_categories.article_id
WHERE article_categories.category_id = 2
ORDER BY articles.article_date DESC";
// Parse query
// (Limited to the clauses that are present in the example...)
// Edit: Made WHERE optional
if(!preg_match('/^\s*'.
'SELECT\s+(?P<select_rows>.*[^\s])'.
'\s+FROM\s+(?P<from>.*[^\s])'.
'(?:\s+WHERE\s+(?P<where>.*[^\s]))?'.
'(?:\s+ORDER\s+BY\s+(?P<order_by>.*[^\s]))?'.
'(?:\s+(?P<desc>DESC))?'.
'(.*)$/is',$sql,$query)
) {
trigger_error('Error parsing SQL!',E_USER_ERROR);
return false;
}
## Dump matches
#foreach($query as $key => $value) if(!is_int($key)) echo "\"$key\" => \"$value\"<br/>\n";
/* We get the following matches:
"select_rows" => "articles.*, formats.format_title"
"from" => "articles INNER JOIN formats ON articles.article_format_id = formats.format_id INNER JOIN article_categories ON articles.article_id = article_categories.article_id"
"where" => "article_categories.category_id = 2"
"order_by" => "articles.article_date"
"desc" => "DESC"
/**/
// Will only support WHERE conditions separated by AND that are to be
// tested on a single individual table.
if(#$query['where']) // Edit: Made WHERE optional
$where_conditions = preg_split('/\s+AND\s+/is',$query['where']);
// Retrieve individual table information & data
$tables = array();
$from_conditions = array();
$from_tables = preg_split('/\s+INNER\s+JOIN\s+/is',$query['from']);
foreach($from_tables as $from_table) {
if(!preg_match('/^(?P<table_name>[^\s]*)'.
'(?P<on_clause>\s+ON\s+(?P<table_a>.*)\.(?P<column_a>.*)\s*'.
'=\s*(?P<table_b>.*)\.(?P<column_b>.*))?$/im',$from_table,$matches)
) {
trigger_error("Error parsing SQL! Unexpected format in FROM clause: $from_table", E_USER_ERROR);
return false;
}
## Dump matches
#foreach($matches as $key => $value) if(!is_int($key)) echo "\"$key\" => \"$value\"<br/>\n";
// Remember on_clause for later jointure
// We do assume each INNER JOIN's ON clause compares left table to
// right table. Forget about parsing more complex conditions in the
// ON clause...
if(#$matches['on_clause'])
$from_conditions[$matches['table_name']] = array(
'column_a' => $matches['column_a'],
'column_b' => $matches['column_b']
);
// Match applicable WHERE conditions
$where = array();
if(#$query['where']) // Edit: Made WHERE optional
foreach($where_conditions as $where_condition)
if(preg_match("/^$matches[table_name]\.(.*)$/",$where_condition,$matched))
$where[] = $matched[1];
$where_clause = empty($where) ? null : implode(' AND ',$where);
// We simply ignore $query[select_rows] and use '*' everywhere...
$query = "SELECT * FROM $matches[table_name]".($where_clause? " WHERE $where_clause" : '');
echo "$query<br/>\n";
// Retrieve table's data
// Fetching the entire table data right away avoids multiplying MySQL
// queries exponentially...
$table = array();
if($results = mysql_query($table))
while($row = mysql_fetch_array($results, MYSQL_ASSOC))
$table[] = $row;
// Sort table if applicable
if(preg_match("/^$matches[table_name]\.(.*)$/",$query['order_by'],$matched)) {
$sort_key = $matched[1];
// #todo Do your bubble sort here!
if(#$query['desc']) array_reverse($table);
}
$tables[$matches['table_name']] = $table;
}
// From here, all data is fetched.
// All left to do is the actual jointure.
/**
* Equijoin/Theta-join.
* Joins relation $R and $S where $a from $R compares to $b from $S.
* #param array $R A relation (set of tuples).
* #param array $S A relation (set of tuples).
* #param string $a Attribute from $R to compare.
* #param string $b Attribute from $S to compare.
* #return array A relation resulting from the equijoin/theta-join.
*/
function equijoin($R,$S,$a,$b) {
$T = array();
if(empty($R) or empty($S)) return $T;
foreach($R as $tupleR) foreach($S as $tupleS)
if($tupleR[$a] == #$tupleS[$b])
$T[] = array_merge($tupleR,$tupleS);
return $T;
}
$jointure = array_shift($tables);
if(!empty($tables)) foreach($tables as $table_name => $table)
$jointure = equijoin($jointure, $table,
$from_conditions[$table_name]['column_a'],
$from_conditions[$table_name]['column_b']);
return $jointure;
?>
Good night, and Good luck!
In instead of the sql rewriting I think you should create a denormalized articles table and change it at each article insert/delete/update. It will be MUCH simpler and cheaper.
Do the create and populate it:
create table articles_denormalized
...
insert into articles_denormalized
SELECT articles.*, formats.format_title
FROM articles
INNER JOIN formats ON articles.article_format_id = formats.format_id
INNER JOIN article_categories ON articles.article_id = article_categories.article_id
Now issue the appropriate article insert/update/delete against it and you will have a denormalized table always ready to be queried.
I have two dynamic tables (tabx and taby) which are created and maintained through a php interface where columns can be added, deleted, renamed etc.
I want to read all columns simulataneously from the two tables like so;-
select * from tabx,taby where ... ;
I want to be able to tell from the result of the query whether each column came from either tabx or taby - is there a way to force mysql to return fully qualified column names e.g. tabx.col1, tabx.col2, taby.coln etc?
In PHP, you can get the field information from the result, like so (stolen from a project I wrote long ago):
/*
Similar to mysql_fetch_assoc(), this function returns an associative array
given a mysql resource, but prepends the table name (or table alias, if
used in the query) to the column name, effectively namespacing the column
names and allowing SELECTS for column names that would otherwise have collided
when building a row's associative array.
*/
function mysql_fetch_assoc_with_table_names($resource) {
// get a numerically indexed row, which includes all fields, even if their names collide
$row = mysql_fetch_row($resource);
if( ! $row)
return $row;
$result = array();
$size = count($row);
for($i = 0; $i < $size; $i++) {
// now fetch the field information
$info = mysql_fetch_field($resource, $i);
$table = $info->table;
$name = $info->name;
// and make an associative array, where the key is $table.$name
$result["$table.$name"] = $row[$i]; // e.g. $result["user.name"] = "Joe Schmoe";
}
return $result;
}
Then you can use it like this:
$resource = mysql_query("SELECT * FROM user JOIN question USING (user_id)");
while($row = mysql_fetch_assoc_with_table_names($resource)) {
echo $row['question.title'] . ' Asked by ' . $row['user.name'] . "\n";
}
So to answer your question directly, the table name data is always sent by MySQL -- It's up to the client to tell you where each column came from. If you really want MySQL to return each column name unambiguously, you will need to modify your queries to do the aliasing explicitly, like #Shabbyrobe suggested.
select * from tabx tx, taby ty where ... ;
Does:
SELECT tabx.*, taby.* FROM tabx, taby WHERE ...
work?
I'm left wondering what you are trying to accomplish. First of all, adding and removing columns from a table is a strange practice; it implies that the schema of your data is changing at run-time.
Furthermore, to query from the two tables at the same time, there should be some kind of relationship between them. Rows in one table should be correlated in some way with rows of the other table. If this is not the case, you're better off doing two separate SELECT queries.
The answer to your question has already been given: SELECT tablename.* to retrieve all the columns from the given table. This may or may not work correctly if there are columns with the same name in both tables; you should look that up in the documentation.
Could you give us more information on the problem you're trying to solve? I think there's a good chance you're going about this the wrong way.
Leaving aside any questions about why you might want to do this, and why you would want to do a cross join here at all, here's the best way I can come up with off the top of my head.
You could try doing an EXPLAIN on each table and build the select statement programatically from the result. Here's a poor example of a script which will give you a dynamically generated field list with aliases. This will increase the number of queries you perform though as each table in the dynamically generated query will cause an EXPLAIN query to be fired (although this could be mitigated with caching fairly easily).
<?php
$pdo = new PDO($dsn, $user, $pass, array(PDO::ATTR_ERRMODE=>PDO::ERRMODE_EXCEPTION));
function aliasFields($pdo, $table, $delim='__') {
$fields = array();
// gotta sanitise the table name - can't do it with prepared statement
$table = preg_replace('/[^A-z0-9_]/', "", $table);
foreach ($pdo->query("EXPLAIN `".$table."`") as $row) {
$fields[] = $table.'.'.$row['Field'].' as '.$table.$delim.$row['Field'];
}
return $fields;
}
$fieldAliases = array_merge(aliasFields($pdo, 'artist'), aliasFields($pdo, 'event'));
$query = 'SELECT '.implode(', ', $fieldAliases).' FROM artist, event';
echo $query;
The result is a query that looks like this, with the table and column name separated by two underscores (or whatever delimeter you like, see the third parameter to aliasFields()):
// ABOVE PROGRAM'S OUTPUT (assuming database exists)
SELECT artist__artist_id, artist__event_id, artist__artist_name, event__event_id, event__event_name FROM artist, event
From there, when you iterate over the results, you can just do an explode on each field name with the same delimeter to get the table name and field name.
John Douthat's answer is much better than the above. It would only be useful if the field metadata was not returned by the database, as PDO threatens may be the case with some drivers.
Here is a simple snippet for how to do what John suggetsted using PDO instead of mysql_*():
<?php
$pdo = new PDO($dsn, $user, $pass, array(PDO::ATTR_ERRMODE=>PDO::ERRMODE_EXCEPTION));
$query = 'SELECT artist.*, eventartist.* FROM artist, eventartist LIMIT 1';
$stmt = $pdo->prepare($query);
$stmt->execute();
while ($row = $stmt->fetch()) {
foreach ($row as $key=>$value) {
if (is_int($key)) {
$meta = $stmt->getColumnMeta($key);
echo $meta['table'].".".$meta['name']."<br />";
}
}
}