var pg = require('pg');
var conString = "postgres://username:password@localhost/databasename";
var client = new pg.Client(conString);
 
var PG = function(){
 console.log("准备向****数据库连接...");
};
 
PG.prototype.getConnection = function(){
 client.connect(function (err) {
 if (err) {
  return console.error('could not connect to postgres', err);
 }
 client.query('SELECT NOW() AS "theTime"', function (err, result) {
  if (err) {
  return console.error('error running query', err);
  }
  console.log("hbdfxt数据库连接成功...");
 });
 });
};
 
// 查询函数
//@param str 查询语句
//@param value 相关值
//@param cb 回调函数
var clientHelper = function(str,value,cb){
 client.query(str,value,function(err,result){
 if(err) {
  cb("err");
 }
 else{
  if(result.rows != undefined)
  cb(result.rows);
  else
  cb();
 }
 });
}
//增
//@param tablename 数据表名称
//@param fields 更新的字段和值，json格式
//@param cb 回调函数
PG.prototype.save = function(tablename,fields,cb){
 if(!tablename) return;
 var str = "insert into "+tablename+"(";
 var field = [];
 var value = [];
 var num = [];
 var count = 0;
 for(var i in fields){
 count++;
 field.push(i);
 value.push(fields[i]);
 num.push("$"+count);
 }
 str += field.join(",") +") values("+num.join(",")+")";
 clientHelper(str,value,cb);
};
 
//删除
//@param tablename 数据表名称
//@param fields 条件字段和值，json格式
//@param cb 回调函数
PG.prototype.remove = function(tablename,fields,cb){
 if(!tablename) return;
 var str = "delete from "+tablename+" where ";
 var field = [];
 var value = [];
 var count = 0;
 for(var i in fields){
 count++;
 field.push(i+"=$" +count);
 value.push(fields[i]);
 }
 str += field.join(" and ");
 clientHelper(str,value,cb);
}
 
//修改
//@param tablename 数据表名称
//@param fields 更新的字段和值，json格式
//@param mainfields 条件字段和值，json格式
PG.prototype.update = function(tablename,mainfields,fields,cb){
 if(!tablename) return;
 var str = "update "+tablename+" set ";
 var field = [];
 var value = [];
 var count = 0;
 for(var i in fields){
 count++;
 field.push(i+"=$"+count);
 value.push(fields[i]);
 }
 str += field.join(",") +" where ";
 field = [];
 for(var j in mainfields){
 count++;
 field.push(j+"=$"+count);
 value.push(mainfields[j]);
 }
 str += field.join(" and ");
 clientHelper(str,value,cb);
}
 
//查询
//@param tablename 数据表名称
//@param fields 条件字段和值，json格式
//@param returnfields 返回字段
//@param cb 回调函数
PG.prototype.select = function(tablename,fields,returnfields,cb){
 if(!tablename) return;
 var returnStr = "";
 if(returnfields.length == 0)
 returnStr = '*';
 else
 returnStr= returnfields.join(",");
 var str = "select "+returnStr+ " from "+tablename+" where ";
 var field = [];
 var value = [];
 var count = 0;
 for(var i in fields){
 count++;
 field.push(i+"=$"+count);
 value.push(fields[i]);
 }
 str += field.join(" and ");
 clientHelper(str,value,cb);
};
 
module.exports = new PG();
 

var pgclient = require('./PG');// 引用上述文件
pgclient.getConnection();
 
// 调用上述四个函数即可
pgclient.save('userinfo',{'name': admin},cb);<span style="font-family: Arial, Helvetica, sans-serif;">.</span>