Skip to content

ErcanOPAK.com

  • ASP.Net WebForms
  • ASP.Net MVC
  • C#
  • SQL
  • MySQL
  • PHP
  • Devexpress
  • Reportviewer
  • About
MySQL / PHP

How do you connect to multiple MySQL databases on a single webpage?

- 05.05.19 | 14.04.20 - ErcanOPAK

You can make multiple calls to mysql_connect(), but if the parameters are the same you need to pass true for the ‘$new_link‘ (fourth) parameter, otherwise the same connection is reused.
For example:

$dbh1 = mysql_connect($hostname, $username, $password); 
$dbh2 = mysql_connect($hostname, $username, $password, true); 

mysql_select_db('database1', $dbh1);
mysql_select_db('database2', $dbh2);

Then to query database 1 pass the first link identifier:

mysql_query('select * from tablename', $dbh1);

and for database 2 pass the second:

mysql_query('select * from tablename', $dbh2);

If you do not pass a link identifier then the last connection created is used (in this case the one represented by $dbh2) e.g.:

mysql_query('select * from tablename');

Other options

If the MySQL user has access to both databases and they are on the same host (i.e. both DBs are accessible from the same connection) you could:

  • Keep one connection open and call mysql_select_db() to swap between as necessary. I am not sure this is a clean solution and you could end up querying the wrong database.
  • Specify the database name when you reference tables within your queries (e.g. SELECT * FROM database2.tablename). This is likely to be a pain to implement.

Related posts:

Navigate to a Div using a button in HTML
How to show a button with condition in PHP
How to connect MySQL Database with PHP
mysql_connect() in PHP 7
Disable REST API Plugin
Post Views: 126

Post navigation

Null-Conditional (?) and Null-Coalescing (??) Operators in C#
Repeater Function in PHP

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

April 2021
M T W T F S S
 1234
567891011
12131415161718
19202122232425
2627282930  
« Jan    

Most Viewed Posts

  • Get the First and Last Word from a String or Sentence in SQL (243)
  • How to use Map Mode for Vertical Scroll Mode in Visual Studio (194)
  • How to make some specific word(s) Bold or Underline in ReportViewer (187)
  • How to solve “Response.Redirect cannot be called in a Page callback” for DevExpress Components (183)
  • Confirm before process with ASPxButton in Devexpress (172)
  • ASPxGridView – Disable CheckBox based on condition in GridViewCommandColumn (170)
  • Find numbers with more than two decimal places in SQL (168)
  • Devexpress ASPxGridview Column Grouping in Code (164)
  • DATEADD Function in SQL (163)
  • Tense Changes When Using Reported Speech (160)

Recent Posts

  • How to check for ‘IS NOT NULL’ And ‘IS NOT EMPTY’ string in SQL
  • How to auto-scroll or manually to end of div when data is added
  • Filter Rows By Max Date in SQL
  • How to Validate a DateTime in C#?
  • Convert comma separated string into a List in C#
  • Converting a List to a comma separated string in C#
  • How to add placeholder to Multiple Selection DropDownList in Asp.Net MVC
  • How to use toFixed() for Float numbers in Javascript
  • Convert List to List in one line in C#
  • How to use column search in datatable when responsive is false

Recent Posts

  • How to check for ‘IS NOT NULL’ And ‘IS NOT EMPTY’ string in SQL
  • How to auto-scroll or manually to end of div when data is added
  • Filter Rows By Max Date in SQL
  • How to Validate a DateTime in C#?
  • Convert comma separated string into a List in C#

Most Viewed Posts

  • Get the First and Last Word from a String or Sentence in SQL (243)
  • How to use Map Mode for Vertical Scroll Mode in Visual Studio (194)
  • How to make some specific word(s) Bold or Underline in ReportViewer (187)
  • How to solve “Response.Redirect cannot be called in a Page callback” for DevExpress Components (183)
  • Confirm before process with ASPxButton in Devexpress (172)

Social

  • ErcanOPAK.com
  • GoodReads
  • LetterBoxD
  • Linkedin
  • The Blog
  • Twitter

powered by XBlog Plus WordPress Theme