I am using Oracle.DataAccess.dll and having this type of Connection string

"User ID=ENET;Password=;Host=xxx.xxx.xxx.xxx:1522;Pooling=true;Min Pool Size=0;Max Pool Size=100;Connection Lifetime=0;"

But it is giving me error as follows ORA-12514:TNS:listener does not currently know of service requested in connected description

I have figure out it is asking about service name My service name is EXTST  But I am not getting that how to put service name parameter in this string. Can some body help me.

If you can do:

TNSPING EXTST

(from command prompt)

than connection string should be:

"User ID=xxxx;Password=yyyy;Data Source=EXTST;Pooling=true;Min Pool Size=0;Max Pool Size=100;Connection Lifetime=0;"

check for this file

C:\Oracle\product\10.1.0\Client_1\NETWORK\ADMIN\tnsnames.ora

here u c

# tnsnames.ora Network Configuration File: F:\oracle\product\10.2.0\client_2\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

POWER =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.202)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = power)
    )
  )

 use POWER (in my scenario) for Data Source = POWER

u will use what u have in ur  file 

Sorry for my English