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I'm stuck with this portion where I know there is definitely a way to do this dynamically, but I just don't know how.
How do I, upon receiving a search query, and knowing how many arrays are in the search query, dynamically creates a SQL string?
Below are parts of the code shown. Any help is appreciated, thanks! =)
if ($arraycount ==2){
$searchSQL = $db->query("SELECT * FROM table WHERE field1 IN (SELECT field2 FROM $table WHERE field3 IN ('$array[0]','$array[1]'));");
}
else if ($arraycount ==3){
$searchSQL = $db->query("SELECT * FROM table WHERE field1 IN (SELECT field2 FROM $table WHERE field3 IN ('$array[0]','$array[1]','$array[2]'));");
}
You can use implode to concatenate values of an array.
$sql = "SELECT * FROM table WHERE field1
(SELECT field2 FROM $table
WHERE field3 IN ('".implode("','", $array)."')";
$searchSQL = $db->query($sql);
Here is Codepad demo.
All credit to #peterm, but with extra security measure (if you use MySQL)
... implode("','", array_map("mysql_real_escape_string", $array))
I was wondering if anyone could help me with this minor problem.
I want to select something from the database, where the number is not more than a set number.
This is what i have (snippet):
$Level = "1"; //Retrieved from the DB, just keeping it simple.
#$Query = mysql_query("SELECT * FROM users,store WHERE users.ID = '$ID' AND store.LevelReq <='users.Level'");
The problem with this, it doesn't display anything that equals $level.
(Item ... Level: 0) - Displays
(Item ... Level: 1) - Doesn't display.
So what i'd like is the equivalent of php's !>1 (not more than 1) but in MYSQL format if possible, however this doesn't work.
You should remember that 'not more than' is always the same as 'lower than and equal to', so you should use field <= value. (So in your case: field <= 1.)
I assume that Level is a field of the table users, if it is true, then you have a quote problem in you query, and query with the PHP var, try:
$Query = #mysql_query("SELECT * FROM users,store WHERE users.ID = '{$ID}' AND store.LevelReq <= {$Level}");
tables and columns are escaped separately, therefor, instead of 'users.Level', try user.'level'. (table.column)
$Level = "1"; //Retrieved from the DB, just keeping it simple.
#$Query = mysql_query("SELECT * FROM users,store WHERE users.ID = '$ID' AND store.LevelReq <= users.'Level'");
You are comparing store.LevelReq to the string "users.Level", not the column users.Level. Remove the quotes around users.Level, and everything should be well!
Are you sure you shouldn't use backticks instead of single quotes? Like this:
$Level = "1"; //Retrieved from the DB, just keeping it simple.
#$Query = mysql_query("SELECT * FROM users,store WHERE users.ID = '$ID' AND store.LevelReq <=`users`.`Level`");
Im trying to pass an array that I already found by a query into another query. For example:
$first_query = "SELECT id FROM from Table WHERE user = '{$_SESSION['id'}'";
$result = mysql_query($first_query,$connection);
$ids = mysql_fetch_array($result);
This is where it gets tricky for me. I want to pass $ids into the next query.
$id_implode = implode(", ", $ids)
$second_query = "SELECT * FROM Table2 WHERE id = '{$id_implode}';
The second query doesnt seem to be working. Any help is greatly appreciated!
your second query's syntax is wrong. Once evaluated it should read
select * from Table2 where id in (1,2,3)
ditch the curly braces and change the = to in. Don't use OR - that's a dumb way of ignoring good sql functionality
EDIT: Teneff's comment makes a very good point - why are you approaching the problem in this way? If there is a relationship between the tables they can be joined and all the data you want can be retrieved in a single query. If for some reason you can't / won't join the tables you could at least try a sub-query
select * from table2 where id in (select id from table where user = $_SESSION['id']);
To use a where statement with multiple entries to match on, use in ().
$id_implode = "'".implode("', '", $ids)."'"
$second_query = "SELECT * FROM Table2 WHERE id in ({$id_implode});
I think you should use IN
$id_implode = implode(", ", $ids)
$second_query = "SELECT * FROM Table2 WHERE id IN '({$id_implode})';
This assumes that $ids is made of int of course, otherwise you have to enclose eache entry in quotes. that means
IN (6,7,8,9)//this doesn't need quotes
IN ('lemon', 'orange')//needs quotes
try to use the IN syntax:
$id_implode = implode("', '", $ids);
$second_query = "SELECT * FROM Table2 WHERE id in ('{$id_implode}');
I'd like to get all of a mysql table's col names into an array in php?
Is there a query for this?
The best way is to use the INFORMATION_SCHEMA metadata virtual database. Specifically the INFORMATION_SCHEMA.COLUMNS table...
SELECT `COLUMN_NAME`
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename'
AND `TABLE_NAME`='yourtablename';
It's VERY powerful, and can give you TONS of information without need to parse text (Such as column type, whether the column is nullable, max column size, character set, etc)...
Oh, and it's standard SQL (Whereas SHOW ... is a MySQL specific extension)...
For more information about the difference between SHOW... and using the INFORMATION_SCHEMA tables, check out the MySQL Documentation on INFORMATION_SCHEMA in general...
You can use the following query for MYSQL:
SHOW `columns` FROM `your-table`;
Below is the example code which shows How to implement above syntax in php to list the names of columns:
$sql = "SHOW COLUMNS FROM your-table";
$result = mysqli_query($conn,$sql);
while($row = mysqli_fetch_array($result)){
echo $row['Field']."<br>";
}
For Details about output of SHOW COLUMNS FROM TABLE visit: MySQL Refrence.
Seems there are 2 ways:
DESCRIBE `tablename`
or
SHOW COLUMNS FROM `tablename`
More on DESCRIBE here: http://dev.mysql.com/doc/refman/5.0/en/describe.html
I have done this in the past.
SELECT column_name
FROM information_schema.columns
WHERE table_name='insert table name here';
Edit: Today I learned the better way of doing this. Please see ircmaxell's answer.
Parse the output of SHOW COLUMNS FROM table;
Here's more about it here: http://dev.mysql.com/doc/refman/5.0/en/show-columns.html
Use mysql_fetch_field() to view all column data. See manual.
$query = 'select * from myfield';
$result = mysql_query($query);
$i = 0;
while ($i < mysql_num_fields($result))
{
$fld = mysql_fetch_field($result, $i);
$myarray[]=$fld->name;
$i = $i + 1;
}
"Warning
This extension is deprecated as of PHP 5.5.0, and will be removed in the future."
The simplest solution out of all Answers:
DESC `table name`
or
DESCRIBE `table name`
or
SHOW COLUMNS FROM `table name`
An old PHP function "mysql_list_fields()" is deprecated. So, today the best way to get names of fields is a query "SHOW COLUMNS FROM table_name [LIKE 'name']". So, here is a little example:
$fields = array();
$res=mysql_query("SHOW COLUMNS FROM mytable");
while ($x = mysql_fetch_assoc($res)){
$fields[] = $x['Field'];
}
foreach ($fields as $f) { echo "<br>Field name: ".$f; }
when you want to check your all table structure with some filed then use this code. In this query i select column_name,column_type and table_name for more details . I use order by column_type so i can see it easily.
SELECT `COLUMN_NAME`,COLUMN_TYPE,TABLE_NAME
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename' order by DATA_TYPE;
If you want to check only double type filed then you can do it easily
SELECT `COLUMN_NAME`,COLUMN_TYPE,TABLE_NAME,DATA_TYPE
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename' AND DATA_TYPE like '%bigint%' order by DATA_TYPE;
if you want to check which field allow null type etc then you can use this
SELECT `COLUMN_NAME`,COLUMN_TYPE,TABLE_NAME,IS_NULLABLE,DATA_TYPE
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename' and DATA_TYPE like '%bigint%' and IS_NULLABLE ='NO' order by COLUMN_TYPE;
you want to check more then thik link also help you.
https://dev.mysql.com/doc/refman/5.7/en/columns-table.html
this generates a string of column names with a comma delimiter:
SELECT CONCAT('(',GROUP_CONCAT(`COLUMN_NAME`),')')
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='database_name'
AND `TABLE_NAME`='table_name';
function get_col_names(){
$sql = "SHOW COLUMNS FROM tableName";
$result = mysql_query($sql);
while($record = mysql_fetch_array($result)){
$fields[] = $record['0'];
}
foreach ($fields as $value){
echo 'column name is : '.$value.'-';
}
}
return get_col_names();
Not sure if this is what you were looking for, but this worked for me:
$query = query("DESC YourTable");
$col_names = array_column($query, 'Field');
That returns a simple array of the column names / variable names in your table or array as strings, which is what I needed to dynamically build MySQL queries. My frustration was that I simply don't know how to index arrays in PHP very well, so I wasn't sure what to do with the results from DESC or SHOW. Hope my answer is helpful to beginners like myself!
To check result: print_r($col_names);
SHOW COLUMNS in mysql 5.1 (not 5.5) uses a temporary disk table.
http://dev.mysql.com/doc/refman/5.1/en/internal-temporary-tables.html
http://dev.mysql.com/doc/refman/5.1/en/show-columns.html
So it can be considered slow for some cases. At least, it can bump up your created_tmp_disk_tables value. Imagine one temporary disk table per connection or per each page request.
SHOW COLUMNS is not really so slow, possibly because it uses file system cache. Phpmyadmin says ~0.5ms consistently. This is nothing compared to 500ms-1000ms of serving a wordpress page. But still, there are times it matters. There is a disk system involvement, you never know what happens when server is busy, cache is full, hdd is stalled etc.
Retrieving column names through SELECT * FROM ... LIMIT 1 was around ~0.1ms, and it can use query cache as well.
So here is my little optimized code to get column names from a table, without using show columns if possible:
function db_columns_ar($table)
{
//returns Array('col1name'=>'col1name','col2name'=>'col2name',...)
if(!$table) return Array();
if(!is_string($table)) return Array();
global $db_columns_ar_cache;
if(!empty($db_columns_ar_cache[$table]))
return $db_columns_ar_cache[$table];
//IMPORTANT show columns creates a temp disk table
$cols=Array();
$row=db_row_ar($q1="SELECT * FROM `$table` LIMIT 1");
if($row)
{
foreach($row as $name=>$val)
$cols[$name]=$name;
}
else
{
$coldata=db_rows($q2="SHOW COLUMNS FROM `$table`");
if($coldata)
foreach($coldata as $row)
$cols[$row->Field]=$row->Field;
}
$db_columns_ar_cache[$table]=$cols;
//debugexit($q1,$q2,$row,$coldata,$cols);
return $cols;
}
Notes:
As long as your tables first row does not contain megabyte range of data, it should work fine.
The function names db_rows and db_row_ar should be replaced with your specific database setup.
IN WORDPRESS:
global $wpdb; $table_name=$wpdb->prefix.'posts';
foreach ( $wpdb->get_col( "DESC " . $table_name, 0 ) as $column_name ) {
var_dump( $column_name );
}
Try this one out I personally use it:
SHOW COLUMNS FROM $table where field REGEXP 'stock_id|drug_name'
This question is old, but I got here looking for a way to find a given query its field names in a dynamic way (not necessarily only the fields of a table). And since people keep pointing this as the answer for that given task in other related questions, I'm sharing the way I found it can be done, using Gavin Simpson's tips:
//Function to generate a HTML table from a SQL query
function myTable($obConn,$sql)
{
$rsResult = mysqli_query($obConn, $sql) or die(mysqli_error($obConn));
if(mysqli_num_rows($rsResult)>0)
{
//We start with header. >>>Here we retrieve the field names<<<
echo "<table width=\"100%\" border=\"0\" cellspacing=\"2\" cellpadding=\"0\"><tr align=\"center\" bgcolor=\"#CCCCCC\">";
$i = 0;
while ($i < mysqli_num_fields($rsResult)){
$field = mysqli_fetch_field_direct($rsResult, $i);
$fieldName=$field->name;
echo "<td><strong>$fieldName</strong></td>";
$i = $i + 1;
}
echo "</tr>";
//>>>Field names retrieved<<<
//We dump info
$bolWhite=true;
while ($row = mysqli_fetch_assoc($rsResult)) {
echo $bolWhite ? "<tr bgcolor=\"#CCCCCC\">" : "<tr bgcolor=\"#FFF\">";
$bolWhite=!$bolWhite;
foreach($row as $data) {
echo "<td>$data</td>";
}
echo "</tr>";
}
echo "</table>";
}
}
This can be easily modded to insert the field names in an array.
Using a simple: $sql="SELECT * FROM myTable LIMIT 1" can give you the fields of any table, without needing to use SHOW COLUMNS or any extra php module, if needed (removing the data dump part).
Hopefully this helps someone else.
if you use php, use this gist.
it can get select fields full info with no result，and all custom fields such as:
SELECT a.name aname, b.name bname, b.*
FROM table1 a LEFT JOIN table2 b
ON a.id = b.pid;
if above sql return no data,will also get the field names aname, bname, b's other field name
just two line:
$query_info = mysqli_query($link, $data_source);
$fetch_fields_result = $query_info->fetch_fields();
This query fetches a list of all columns in a database without having to specify a table name. It returns a list of only column names:
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = 'db_name'
However, when I ran this query in phpmyadmin, it displayed a series of errors. Nonetheless, it worked. So use it with caution.
if you only need the field names and types (perhaps for easy copy-pasting into Excel):
SELECT COLUMN_NAME, DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA='databasenamegoeshere'
AND DATA_TYPE='decimal' and TABLE_NAME = 'tablenamegoeshere'
remove
DATA_TYPE='decimal'
if you want all data types
i no expert, but this works for me..
$sql = "desc MyTable";
$result = #mysql_query($sql);
while($row = #mysql_fetch_array($result)){
echo $row[0]."<br>"; // returns the first column of array. in this case Field
// the below code will return a full array-> Field,Type,Null,Key,Default,Extra
// for ($c=0;$c<sizeof($row);$c++){echo #$row[$c]."<br>";}
}
I have tried this query in SQL Server and this worked for me :
SELECT name FROM sys.columns WHERE OBJECT_ID = OBJECT_ID('table_name')
The call of DESCRIBE is working fine to get all columns of a table but if you need to filter on it, you need to use the SHOW COLUMNS FROM instead.
Example of PHP function to get all info of a table :
// get table columns (or return false if table not found)
function get_table_columns($db, $table) {
global $pdo;
if($cols = $pdo->query("DESCRIBE `$db`.`$table`")) {
if($cols = $cols->fetchAll(PDO::FETCH_ASSOC)) {
return $cols;
}
}
return false;
}
In my case, I had to find the primary key of a table. So, I used :
SHOW COLUMNS FROM `table` WHERE `Key`='PRI';
Here is my PHP function :
// get table Primary Key
function get_table_pk($db, $table) {
global $pdo;
$q = "SHOW COLUMNS FROM `$db`.`$table` WHERE `Key` = 'PRI'";
if($cols = $pdo->query($q)) {
if($cols = $cols->fetchAll(PDO::FETCH_ASSOC)) {
return $cols[0];
}
}
return false;
}
look at this table please
table
|id| |name| |order|
i must get the rows, where name = something and order = somevalue
so i write
select `id` from `table` where `name` = 'something' and `order` = 'somevalue'
but depend on php logic, sometimes i need to get all rows, where name = something, independently of order value. i don't want to change the query structure, because in practise there are many number of fields, and possible count of queries will become very big. so i want to save the structure of query, and when i need to select just by name, i want to write something like this:
select `id` from `table` where `name` = 'something' and `order` = any value
is it possible?
thanks
Well, it's kind of a hack, but if you really need to do this, it'll work like this:
select `id` from `table` where `name` = 'something' and `order` = `order`
Then you're just saying "wherever order is the same as itself", so it's always true.
No, this is not possible. You need to change the structure (optionally to a LIKE so you can use '%', but that's very ugly).
However, you don't need to write a different query to handle every possible combination. You can simply create the query dynamically:
//create base query
$query = "select `id` from `table` where `name` = 'something' ";
//add order if we need it
if ($use_order)
$query .= "and `order` = 'somevalue' ";
//repeat for any other optional part
Note that you should of course still take proper measures to avoid SQL injection and other security issues - I have not included this here in order to keep things simple.
If you are using bound parameters, it would be impossible.
If you just substitute the values, you can do the following:
select `id` from `table` where `name` = 'something' and `order` = `order`
This is a common theme with database queries - you need a variable query depending on how much filtering you wish to apply to the data it queries. You could go the route of having your query repeated as a string throughout your code, but that is bad practice as it increases the complexity of the code needlessly. Chances for errors occur if you need to change the query for some reason, and have to change it in multiple places as a result.
The better solution is to create a function which builds the query for you execute:
function buildMyQuery($name, $order = null) {
$sql = "SELECT `id` FROM `table` WHERE `name`='$name'";
if ($order != null) {
$sql .= " AND `order`='$order'";
}
return $sql;
}
You could then run this for just using the 'name' field:
$query = buildMyQuery("somename");
Or this for using both fields:
$query = buildMyQuery("somename", "someorder");
As someone mentioned above, this code is deliberately simplified and contains no contingency for possibly dangerous data passed in via $name or $order. You would need to use mysql_real_escape_string or something similar to clean the data first, at the beginning of the function before either piece of data is used.
Dynamic query generation is a fact of life as Byron says, so I would become accustomed to it now rather than using hack-ish workarounds.
I don't think you have any choice... Once you do a selection you can't "unfilter" and get more rows.
You should just use two queries-- either two independent queries, or one that selects on the name into a temp table, and then (optionally) one that further selects on the order attribute.
Like Chad said above, just set the column equal to itself. But be careful, on some platforms / install configurations, NULL != NULL:
select `id` from `table` where `name` = 'something' and coalesce(`order`,'') = coalesce(`order`,'')
On reflection, I have a better answer. My colleague showed me a way this can be done.
My example...
Select rentals.* From rentals Where ((? = '') OR (user_id = ?))
The variables must be the same.
If they are both 5 for example, the first boolean will be false, but the second will be true, for the rows where the users id is 5.
If you require "all", setting as an empty string will result in all rows being seen to meet the where clause condition.
Can't you just use a not null query here?
select `id` from `table` where `name` = 'something' and `order` is not null;
You should be able to do it like this:
select `id` from `table` where `name` <>'' and `order` <>''
That will select anywhere that the value is not equal to blank.
$sql = "SELECT * FROM auctions WHERE id = id ";
if ($category !== "ANY") {
$sql .= "AND category = $category "; }
if ($subcategory !== "ANY") {
$sql .= "AND subcategory = $subcategory "; }
if ($country !== "ANY") {
$sql .= "AND country = $country "; }
$sql .= "ORDER BY $order $sort LIMIT $limit OFFSET $offset";