I can do this all as one function, but in trying to port it over to my packages of functions (library) I am missing something.
Here's what I want to do from my main Perl script
my #rows;
$result = Funx::dbcdata($myConnection,
"SELECT * FROM Inv where name like \"%DOG%\";", \#rows);
Then in my library package I am attempting this
sub dbcdata
{
my ($connection, $command, $array) = #_;
my $query = $connection->prepare($command);
my $result = $query->execute();
my $i =0;
while(my $row = $query->fetchrow_arrayref() )
{
#{$array}[$i] = $row;
$i++;
}
$query->finish;
return $result;
}
I was hoping to get back pointers or references to each row (which was 4in this case) but am not. Every element in #rows is the same:
ARRAY(0x5577a0f77ec0) ARRAY(0x5577a0f77ec0) ARRAY(0x5577a0f77ec0)
ARRAY(0x5577a0f77ec0)
Nor do I know how to turn each one into the original separate row. Any help would be appreciated, thanks.
From the documentation for fetchrow_arrayref:
Note that the same array reference is returned for each fetch, so don't store the reference and then use it after a later fetch. Also, the elements of the array are also reused for each row, so take care if you want to take a reference to an element.
Sounds like you want fetchall_arrayref:
The fetchall_arrayref method can be used to fetch all the data to be returned from a prepared and executed statement handle. It returns a reference to an array that contains one reference per row.
After executing the statement, you can do something like
#{$array} = $query->fetchall_arrayref->#*;
instead of that ugly loop.
But selectall_array might be even better. Your whole function can be replaced by a call to it:
my #rows =
$myConnection->selectall_array(q/SELECT * FROM Inv WHERE name LIKE '%DOG%'/);
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;
}
I'm pretty new to using WordPress and am having an issue with getting my expected result. I am trying to pull from the WordPress database so I am using $wpdb. The following is what I have:
global $wpdb;
echo $wpdb->query("SELECT * FROM wp_users");
Rather than it echoing all of the users, it returns with the number of users in the table. If I add "WHERE id = some number" it echoes that ID number.
What is going wrong and how do I get it to select all from that table?
Thanks.
The function returns an integer corresponding to the number of rows
affected/selected. If there is a MySQL error, the function will return
FALSE. (Note: since both 0 and FALSE can be returned, make sure you
use the correct comparison operator: equality == vs. identicality ===)
You can use get_results to fetch all records
global $wpdb;
$users=$wpdb->get_results( "SELECT * FROM wp_users" );
print_r( $users);
Manual Class_Reference wpdb
I have two mysql commands. I want to create a subroutine with these two mysql commands for the rest of my data that I have to search through. I have a lot of entries. Is there a way to create a subroutine such that in place of the actual numbers and characters I put in my two mysql commands, I put in variables that I can replace so I can then copy and paste the actual values of those variables and the commands are executed for the remaining entries?
For example, I have a command that says
$sth = $dbh->prepare ("select name from table1 where number > 5");
$sth->execute();
#row;
while (#row = $sth->fetchrow_array) {
print "$row[0]\tquestion1\n";
In place of the "5" listed in the select command and "question1" listed in the print command, I want to put something in place of it like "variables" so that I can create a subroutine with these commands in it, but you execute and can run the subroutine over and over by plugging in different values for those variables.
something like this: $dbh = DBI->connect($dsn, $user, $password);
not sure how to go about doing this for mysql perl.
You can use placeholders in your query to use different values in a search.
$sth = $dbh->prepare ("select name from table1 where number > ?");
$sth->execute(5);
After that, it should be trivial to make a subroutine for your print.
For example:
my #values = qw(5 10 15 20);
my #fields = qw(question1 question2);
# ... other code..
my $sth = $dbh->prepare ("select name from table1 where number > ?");
for my $field (#fields) {
for my $value (#values) {
printfields($sth, $value, $field);
}
}
sub printfields {
my ($sth, $value, $field) = #_;
$sth->execute($value);
while (my #row = $sth->fetchrow_array) {
print "$row[0]\t$field\n";
}
}
I prefer to build the select query before running prepare(). Then passing it into prepare() as a scalar. You could also add placeholders in the scalar (if you don't want to simply rebuild it for each query) that could easily be replaced via calls of s///;, which could be easily named/identified as well. This would make the code a bit easier to read than passing bare values to execute().
I'm new in mysql language and can not understand difference between procedures and functions, can anyone answer in which case should be use this routines ?
Also have some example => I've table named "data" and columns named "id"(primary key) , "local". this local includes multiple exactly same data. I want to search every id of this "data" (and after result manipulate with it) table which local equal to (for instance) 'something'
Please answer in this question ... Thanks
Functions:
select <function>(column) from table where <condition>;
Procedure:
call <procedure>( param0, param1 );
To get your result:
select * from <table> where data like "%something%";
I suppose that you use php with mysql.
your query should be
$result = mysql_query("SELECT * FROM data WHERE local='something'");
while($row = mysql_fetch_array($result))
{
// here you manipulate with your data
// for example:
echo $row['id'];
}