QTP supports interaction with Database using ADODB.

Set con = createobject("ADODB.Connection")
Set rs = createobject("ADODB.Recordset")

'Create DSN(DataSourceName) for your database and specify 
the DSN here
'You can also establish connection using Provider name

con.open "DSN=MyDsn;UID=ravi;PWD=sample123"

con.execute "Insert into emp values(2500, 'Ravi')"

'Retrieve data from database
rs.open "select * from emp", con
while not rs.eof
  msgbox "ID = " & rs(0) & " Name = " & rs(1)
  rs.movenext
wend

You can write OLEDB script:

Set Con =CreateObject("ADODB.Connection")
ConString="Provider:SQLNCLI;Server=plantdev;DataBase=QAServe
r;UID=patil;PWD=password1"
Con.ConnectionString=ConString
Con.Open