Pecl PDO package is now deprecated. By the way the debian package php5-pgsql now includes both the regular and the PDO driver, so just:

    apt-get install php-pgsql

Apache also needs to be restarted before sites can use it:

    sudo systemctl restart apache2

Try the packaged pecl version instead (the advantage of the packaged installs is that they&#39;re easier to upgrade):

    apt-get install php5-dev
    pecl install pdo
    pecl install pdo_pgsql

or, if you just need *a* driver for PHP, but that it doesn&#39;t have to be the PDO one:

    apt-get install php5-pgsql

----------

Otherwise, that message most likely means you need to install a more recent libpq package.
You can check which version you have by running:

    dpkg -s libpq-dev

If you&#39;re using the wonderful `ondrej/php` ubuntu repository with php7.0:

    sudo apt-get install php7.0-pgsql

For `ondrej/php` Ubuntu repository with php7.1:

    sudo apt-get install php7.1-pgsql

Same repository, but for php5.6:

    sudo apt-get install php5.6-pgsql

Concise and easy to remember. I love this repository.

PDO driver for PostgreSQL is now included in the debian package php5-dev. The above steps using Pecl no longer works.

If you are using PHP 5.6, the command is:

    sudo apt-get install php5.6-pgsql

I&#39;ve read the Roxygen2 PDF and this [site][1], and I&#39;m lost on the difference between @method @S3method @export and how to use these to properly document S3 methods. I worked up the follow example for discussion:&lt;br/&gt;&lt;br/&gt;
1. How would I properly document these?&lt;br/&gt;&lt;br/&gt;
2. How do I emulate documentation of ?print and other generic functions that show the use cases for all class-specific implimentations (i.e. the way ?print shows usage for &#39;factor&#39;, &#39;table&#39;,&#39;function&#39;)&lt;br/&gt;&lt;br/&gt;
3. From the wiki page: &quot;All exported methods need the @S3method tag. It has the same format as @method. This exports the method, not the function - i.e. generic(myobject) will work, but generic.mymethod(myobject) will not.&quot;&lt;br/&gt;
I can&#39;t interpret this.  This seems to say that function/method calls won&#39;t work properly if the tags are improperly specified?  What specifically will break?

    MyHappyFunction = function( x , ... )
    {
        UseMethod( &quot;MyHappyFunction&quot; )
    }
    
    MyHappyFunction.lm = function( x , ... )
    {
      # do some magic
    }


  [1]: https://github.com/hadley/devtools/wiki/docs-function


Roxygen2 - how to properly document S3 methods

I&#39;m trying to get the SHA256 of a string in Android.

Here is the PHP code that I want to match:

    echo bin2hex(mhash(MHASH_SHA256,&quot;asdf&quot;));
    //outputs &quot;f0e4c2f76c58916ec258f246851bea091d14d4247a2fc3e18694461b1816e13b&quot;

Now, in Java, I&#39;m trying to do the following:

     
                String password=&quot;asdf&quot;
                MessageDigest digest=null;
		try {
			digest = MessageDigest.getInstance(&quot;SHA-256&quot;);
		} catch (NoSuchAlgorithmException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	       digest.reset();
	       try {
			Log.i(&quot;Eamorr&quot;,digest.digest(password.getBytes(&quot;UTF-8&quot;)).toString());
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

But this prints out: &quot;a42yzk3axdv3k4yh98g8&quot;

What did I do wrong here?

------------------------------------------------------
Solution thanks to erickson:

     

     Log.i(&quot;Eamorr&quot;,bin2hex(getHash(&quot;asdf&quot;)));

     public byte[] getHash(String password) {
	       MessageDigest digest=null;
		try {
			digest = MessageDigest.getInstance(&quot;SHA-256&quot;);
		} catch (NoSuchAlgorithmException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	       digest.reset();
	       return digest.digest(password.getBytes());
	 }
	static String bin2hex(byte[] data) {
		return String.format(&quot;%0&quot; + (data.length*2) + &quot;X&quot;, new BigInteger(1, data));
	}



How can I calculate the SHA-256 hash of a string in Android?

I am trying to enable the pdo driver for my php installation, but when I runn the command


    ./configure --prefix=/usr/local/webserver/php --with-apxs2=/usr/local/webserver/apache2/bin/apxs --enable-mbstring --enable-intl --with-icu-dir=/usr --with-pgsql=/usr/local/webserver/postgres --with-pdo-pgsql=/usr/local/webserver/postgres

I get

    &quot;Unable to build the PDO PostgreSQL driver: libpq 7.4+ is required&quot;

I install postgresql in that directory

    /usr/local/webserver/postgres

I installed postgresql 9.0.4.1 using the bin package and using php 5.3

Install pdo for postgres Ubuntu

I am trying to enable the pdo driver for my php installation, but when I runn the command
<pre><code class="hljs language-javascript">./configure --prefix=/usr/local/webserver/php --with-apxs2=/usr/local/webserver/apache2/bin/apxs --enable-mbstring --enable-intl --with-icu-dir=/usr --with-pgsql=/usr/local/webserver/postgres --with-pdo-pgsql=/usr/local/webserver/postgres
</code></pre>
I get
<pre><code class="hljs language-arduino">"Unable to build the PDO PostgreSQL driver: libpq 7.4+ is required"
</code></pre>
I install postgresql in that directory
<pre><code class="hljs language-bash">/usr/local/webserver/postgres
</code></pre>
I installed postgresql 9.0.4.1 using the bin package and using php 5.3

I want to create a column `element_type` in a table (called `discussion`) that allows the text values &quot;lesson&quot; or &quot;quiz&quot; but will generate an error if any other value is inserted into that column.

I understand that I could create a separate table called `element_types` with columns `element_id` (primary key, int) and `element_type` (unique, text) and create a foreign key `foreign_element_id` in the table `discussion` referencing `element_types`&#39;s column `element_id`.  Or alternatively, I could forget `element_id` altogether and just set `element_type` as the primary key.  But I want to avoid creating a new table.

Is there a more straightforward way to restrict possible values in a column without creating a new table?

In Postgres, how do you restrict possible values for a particular column?

Postgres can round (truncate) timestamps using the date_trunc function, like this:

    date_trunc(&#39;hour&#39;, val)
    date_trunc(&#39;minute&#39;, val)

I&#39;m looking for a way to truncate a timestamp to the nearest 5-minute boundary so, for example, 14:26:57 becomes 14:25:00.  The straightforward way to do it is like this:

    date_trunc(&#39;hour&#39;, val) + date_part(&#39;minute&#39;, val)::int / 5 * interval &#39;5 min&#39;

Since this is a performance-critical part of the query, I&#39;m wondering whether this is the fastest solution, or whether there&#39;s some shortcut (compatible with Postgres 8.1+) that I&#39;ve overlooked.

What is the fastest way to truncate timestamps to 5 minutes in Postgres?

What is the fastest way to unwrap array into rows in PostgreSQL? For instance,

We have:

    a
    -
    {1,2}
    {2,3,4}

And we need:

    b
    - 
    1
    2
    2
    3
    4

I&#39;m using:
 
    select explode_array(a) as a from a_table;

where explode_array is:

    create or replace function explode_array(in_array anyarray) returns setof anyelement as
    $$
        select ($1)[s] from generate_series(1,array_upper($1, 1)) as s;
    $$

Is there any better way?

unwrap postgresql array into rows

Table &#39;animals&#39;:

    animal_name animal_type
    Tom         Cat
    Jerry       Mouse
    Kermit      Frog
    
Query:

    SELECT 
    array_to_string(array_agg(animal_name),&#39;;&#39;) animal_names,
    array_to_string(array_agg(animal_type),&#39;;&#39;) animal_types
    FROM animals;
    
Expected result:

    Tom;Jerry;Kerimt, Cat;Mouse;Frog
    OR
    Tom;Kerimt;Jerry, Cat;Frog;Mouse
    
    
Can I be sure that order in first aggregate function  will always be the same as in second.
I mean I would&#39;t like to get:
    
    Tom;Jerry;Kermit, Frog;Mouse,Cat



PostgreSQL array_agg order

How can I query all GRANTS granted to an object in postgres?

For example I have table &quot;mytable&quot;:

    GRANT SELECT, INSERT ON mytable TO user1
    GRANT UPDATE ON mytable TO user2 

I need somthing which gives me:

    user1: SELECT, INSERT
    user2: UPDATE



Query grants for a table in postgres

    try {
    	$db = new PDO(&quot;mysql:host=&quot;.HOST.&quot;;dbname=&quot;.DB, USER, PW);
    	$st = $db-&gt;prepare(&quot;SELECT * FROM c6ode&quot;);
    }
    catch (PDOException $e){
    	echo $e-&gt;getMessage();
    }

How can I check the mysql error for the query in above case? 

How to view query error in PDO PHP

This is what I&#39;ve read so far about [`PDO::ATTR_EMULATE_PREPARES`](http://www.php.net/manual/en/pdo.setattribute.php):

1. [PDO&#39;s prepare emulation is better for performance since MySQL&#39;s native prepare bypasses the query cache][1].
2. [MySQL&#39;s native prepare is better for security (preventing SQL Injection)][2].
3. [MySQL&#39;s native prepare is better for error reporting][3].

I don&#39;t know how true any of these statements are anymore. My greatest concern in choosing a MySQL interface is preventing SQL Injection. The second concern is performance.

My application currently uses procedural MySQLi (without prepared statements), and utilizes the query cache quite a bit. It will rarely re-use prepared statements in a single request. I started the move to PDO for the named parameters and security of prepared statements.

I&#39;m using `MySQL 5.1.61` and `PHP 5.3.2`

Should I leave `PDO::ATTR_EMULATE_PREPARES` enabled or not? Is there a way to have both the performance of the query cache and the security of prepared statements?

  [1]: https://stackoverflow.com/a/5751895
  [2]: https://stackoverflow.com/a/1314549
  [3]: https://stackoverflow.com/questions/3727186/the-way-pdo-parametrized-query-works

PDO MySQL: Use PDO::ATTR_EMULATE_PREPARES or not?

    &lt;?php

    try {
       $dbh = new PDO(&#39;pgsql:host=localhost;port=5432;dbname=###;user=###;password=##&#39;);
       echo &quot;PDO connection object created&quot;;
    }
    catch(PDOException $e)
    {
          echo $e-&gt;getMessage();
    }

    ?&gt;

I get the error message &quot;Could Not Load Driver&quot;

How do I enable php to work with postgresql?

I have a query, and I want to get the last ID inserted. The field ID is the primary key and auto incrementing.

I know that I have to use this statement:

    LAST_INSERT_ID()

That statement works with a query like this:

    $query = &quot;INSERT INTO `cell-place` (ID) VALUES (LAST_INSERT_ID())&quot;;

But if I want to get the ID using this statement:

    $ID = LAST_INSERT_ID();

I get this error:

    Fatal error: Call to undefined function LAST_INSERT_ID()

What am I doing wrong?

PDO get the last ID inserted

From time to time I see questions regarding connecting to database.  
Most answers is not the way I do it, or I might just not get the answers correctly. Anyway; I&#39;ve never thought about it because the way I do it works for me.

But here&#39;s a crazy thought; Maybe I&#39;m doing this all wrong, and if that&#39;s the case; I would really like to know how to properly connect to a MySQL database using PHP and PDO and make it easy accessible.

**Here&#39;s how I&#39;m doing it:**

First off, here&#39;s my file structure *(stripped down)*:

    public_html/

    * index.php  

    * initialize/  
      -- load.initialize.php  
      -- configure.php  
      -- sessions.php   

**index.php**  
At the very top, I have `require(&#39;initialize/load.initialize.php&#39;);`.  

**load.initialize.php**  

    #   site configurations
        require(&#39;configure.php&#39;);
    #   connect to database
        require(&#39;root/somewhere/connect.php&#39;);  //  this file is placed outside of public_html for better security.
    #   include classes
        foreach (glob(&#39;assets/classes/*.class.php&#39;) as $class_filename){
            include($class_filename);
        }
    #	include functions
        foreach (glob(&#39;assets/functions/*.func.php&#39;) as $func_filename){
            include($func_filename);
        }
    #	handle sessions
        require(&#39;sessions.php&#39;);

*I know there&#39;s a better, or more correct, way to include classes, but can&#39;t remember what it was. Haven&#39;t gotten the time to look into it yet, but I think it was something with `autoload`. something like that...*

**configure.php**  
Here I basically just override some *php.ini*-properties and do some other global configuration for the site

**connect.php**  
I&#39;ve put the connection onto a class so other classes can *extends* this one...

    class connect_pdo
    {
        protected $dbh;

        public function __construct()
        {
            try {
                $db_host = &#39;  &#39;;  //  hostname
                $db_name = &#39;  &#39;;  //  databasename
                $db_user = &#39;  &#39;;  //  username
                $user_pw = &#39;  &#39;;  //  password

                $con = new PDO(&#39;mysql:host=&#39;.$db_host.&#39;; dbname=&#39;.$db_name, $db_user, $user_pw);  
                $con-&gt;setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
                $con-&gt;exec(&quot;SET CHARACTER SET utf8&quot;);  //  return all sql requests as UTF-8  
            }
            catch (PDOException $err) {  
                echo &quot;harmless error message if the connection fails&quot;;
                $err-&gt;getMessage() . &quot;&lt;br/&gt;&quot;;
                file_put_contents(&#39;PDOErrors.txt&#39;,$err, FILE_APPEND);  // write some details to an error-log outside public_html  
                die();  //  terminate connection
            }
        }

        public function dbh()
        {
            return $this-&gt;dbh;
        }
    }
    #   put database handler into a var for easier access
        $con = new connect_pdo();
        $con = $con-&gt;dbh();
    //



*Here I do believe there&#39;s room for massive improvement since I recently started learning OOP, and using PDO instead of mysql.  
So I&#39;ve just followed a couple of beginners tutorials and tried out different stuff...*

**sessions.php**  
Beside handling regular sessions, I also initialize some classes into a session like this:  

    if (!isset($_SESSION[&#39;sqlQuery&#39;])){
        session_start();
        $_SESSION[&#39;sqlQuery&#39;] = new sqlQuery();
    }

This way this class is available all over the place. This might not be good practice(?)...  
Anyway, this is what this approach allows me to do from everywhere:

    echo $_SESSION[&#39;sqlQuery&#39;]-&gt;getAreaName(&#39;county&#39;,9);  // outputs: Aust-Agder (the county name with that id in the database)

Inside my `sqlQuery`-*class*, which `extends` my `connect_pdo`-*class*, I have a public function called `getAreaName` which handles the request to my database.  
Pretty neat I think.


**Works like a charm**  
So that&#39;s basically how I&#39;m doing it.  
Also, whenever I need to fetch something from my DB from not within a class, I just do something similar to this:

    $id = 123;
    
    $sql = &#39;SELECT whatever FROM MyTable WHERE id = :id&#39;;
    $qry = $con-&gt;prepare($sql);
    $qry -&gt; bindParam(&#39;:id&#39;, $id, PDO::PARAM_INT);
    $qry -&gt; execute();
    $get = $qry-&gt;fetch(PDO::FETCH_ASSOC);
 
Since I put the connection into a variable inside *connect_pdo.php*, I just have referring to it and I&#39;m good to go. It works. I get my expected results...

But regardless of that; I would really appreciate if you guys could tell me if I&#39;m way off here. What I should do instead, areas I could or should change for improvement etc... 

I&#39;m eager to learn...

Content Type	Original Author	Original Content on Stackoverflow
Question	Richard Pérez	View Question on Stackoverflow
Solution 1 - Postgresql	Alex	View Answer on Stackoverflow
Solution 2 - Postgresql	wildpeaks	View Answer on Stackoverflow
Solution 3 - Postgresql	Dylan Pierce	View Answer on Stackoverflow
Solution 4 - Postgresql	Will	View Answer on Stackoverflow
Solution 5 - Postgresql	joan16v	View Answer on Stackoverflow

Install pdo for postgres Ubuntu

Postgresql Problem Overview

Postgresql Solutions

Solution 1 - Postgresql

Solution 2 - Postgresql

Solution 3 - Postgresql

Solution 4 - Postgresql

Solution 5 - Postgresql

How can I calculate the SHA-256 hash of a string in Android?

Roxygen2 - how to properly document S3 methods

Attributions