How to add an auto-incrementing primary key to an existing table, in PostgreSQL

function processSQLFile(fileName) {

  // Extract SQL queries from files. Assumes no ';' in the fileNames
  var queries = fs.readFileSync(fileName).toString()
    .replace(/(\r\n|\n|\r)/gm," ") // remove newlines
    .replace(/\s+/g, ' ') // excess white space
    .split(";") // split into all statements
    .map(Function.prototype.call, String.prototype.trim)
    .filter(function(el) {return el.length != 0}); // remove any empty ones

  // Execute each SQL query sequentially
  queries.forEach(function(query) {
    batch.push(function(done) {
      if (query.indexOf("COPY") === 0) { // COPY - needs special treatment
        var regexp = /COPY\ (.*)\ FROM\ (.*)\ DELIMITERS/gmi;
        var matches = regexp.exec(query);
        var table = matches[1];
        var fileName = matches[2];
        var copyString = "COPY " + table + " FROM STDIN DELIMITERS ',' CSV HEADER";
        var stream = client.copyFrom(copyString);
        stream.on('close', function () {
          done();
        });
        var csvFile = __dirname + '/' + fileName;
        var str = fs.readFileSync(csvFile);
        stream.write(str);
        stream.end();
      } else { // Other queries don't need special treatment
        client.query(query, function(result) {
          done();
        });
      }
    });
  });
}

SQL> with t1(col) as(
  2    select 1    from dual union all
  3    select 2    from dual union all
  4    select null from dual union all
  5    select 3    from dual
  6  )
  7  select *
  8    from t1
  9  order by col asc nulls last
  10  ;

select ord_num, agent_code, ord_date, ord_amount
from orders
where(agent_code, ord_amount) IN
(SELECT agent_code, MIN(ord_amount)
FROM orders 
GROUP BY agent_code);  

ALTER TABLE stars
ALTER COLUMN name TYPE varchar(50);

DECLARE @AnyDate DATETIME
SET @AnyDate = GETDATE()

SELECT @AnyDate AS 'Input Date',
  DATEADD(q, DATEDIFF(q, 0, @AnyDate), 0) 
                        AS 'Quarter Start Date',       
  DATEADD(d, -1, DATEADD(q, DATEDIFF(q, 0, @AnyDate) + 1, 0)) 
                        AS 'Quarter End Date'

DECLARE @Year DATE = '2013-01-01'
DECLARE @Quarter INT = 4;

SELECT  DATEADD(QUARTER, @Quarter - 1, @Year) ,
        DATEADD(DAY, -1, DATEADD(QUARTER,  @Quarter, @Year))

SELECT title, extract("year" from current_date) - "year" AS age
  FROM films
  ORDER BY age ASC;

postgres-# ( terminal commands)
- list all databases : \l
- list of all tables : \d
- list only the tables : \dt
- list all fields in a table : \d person (name of the table)
- import from external file : \i c:/postgrescourse/person.sql

- datatypes info:
bigserial : increment int in sequence
date : year,month,day



- create database : create database test;
- drop database : drop database test;
- drop table : drop table person;
- connect to a database ( two forms ) :  
\c test (or) -h localhost -p 5432 -U postgres test
- create table sintax : create table table_name ( column name + data type + constraints if any ) 

- create table : 
create table person ( 
	id int,
	first_name varchar(50),
  	last_name varchar(50),
    gender varchar(6),
    date_of_birth date
    );
- create table w/constraints ( need to satisfied rules): 
create table person (
 	id bigserial not null primary key,
 	first_name varchar(50) not null,
 	last_name varchar(50) not null,
    gender varchar(6) not null, 
    date_of_birth date not null
	);

- create table : 
insert into person ( first_name, last_name, gender, date_of_birth) values ('Anne','Smith','Female',date '1988-01-09');

- Using OFFSET and LIMIT : select * from person OFFSET 5 LIMIT 5;
- Using OFFSET and FETCH : select * from person OFFSET 5 FETCH 5 ROW ONLY;
- Using BETWEEN : select * from person where date_of_birth BETWEEN DATE '2000-01-01' and '2015-01-01';
- Diferences between LIKE and ILIKE : ILIKE is case insensitive. 

- Using Group By : select country_of_birth, count(*) from person group by country_of_birth; ( will count how many people are from that country )
- Using Having with Group By : select country_of_birth, count(*) from person having count(*) > 5 group by country_of_birth; ( must have above 5 to show )

 USE Your_Database;
 GO
 EXECUTE AS USER = N'the_user_name';
 GO
 SELECT 
    s.name,
    o.name,
    p.[permission_name]
 FROM sys.objects AS o 
 INNER JOIN sys.schemas AS s
 ON o.[schema_id] = s.[schema_id]
 CROSS APPLY sys.fn_my_permissions(QUOTENAME(s.name) 
   + N'.' + QUOTENAME(o.name), N'OBJECT') AS p
   WHERE o.[type] IN (N'U', N'V') -- tables and views
   AND p.subentity_name = N''; -- ignore column permissions 
 GO
 REVERT;

SELECT setval(
        pg_get_serial_sequence('TABLE','COLUMN'), 
        max(id)) 
FROM TABLE;

<?php
$results = $wpdb->get_results( "SELECT * FROM $table_name"); // Query to fetch data from database table and storing in $results
if(!empty($results))                        // Checking if $results have some values or not
{    
    echo "<table width='100%' border='0'>"; // Adding <table> and <tbody> tag outside foreach loop so that it wont create again and again
    echo "<tbody>";      
    foreach($results as $row){   
    $userip = $row->user_ip;               //putting the user_ip field value in variable to use it later in update query
    echo "<tr>";                           // Adding rows of table inside foreach loop
    echo "<th>ID</th>" . "<td>" . $row->id . "</td>";
    echo "</tr>";
    echo "<td colspan='2'><hr size='1'></td>";
    echo "<tr>";        
    echo "<th>User IP</th>" . "<td>" . $row->user_ip . "</td>";   //fetching data from user_ip field
    echo "</tr>";
    echo "<td colspan='2'><hr size='1'></td>";
    echo "<tr>";        
    echo "<th>Post ID</th>" . "<td>" . $row->post_id . "</td>";
    echo "</tr>";
    echo "<td colspan='2'><hr size='1'></td>";
    echo "<tr>";        
    echo "<th>Time</th>" . "<td>" . $row->time . "</td>";
    echo "</tr>";
    echo "<td colspan='2'><hr size='1'></td>";
    }
    echo "</tbody>";
    echo "</table>"; 

}
?>

SELECT column-names
  FROM table-name1
 WHERE value IN (SELECT column-name
                   FROM table-name2
                  WHERE condition)

SELECT Fname, Lname
FROM Employee
ORDER BY Salary
OFFSET 2 ROWS;

select schema_name(tab.schema_id) as [schema_name], 
    tab.[name] as table_name
from sys.tables tab
    left outer join sys.indexes pk
        on tab.object_id = pk.object_id 
        and pk.is_primary_key = 1
where pk.object_id is null
order by schema_name(tab.schema_id),
    tab.[name]

DELETE FROM [dbo].[logs] WHERE date < DATEADD(DAY, -30, GETDATE())