you have this in your table
-----------------------------
'smnith', 12345, '06/01/08'
'bobby', 1234, 'fellowbobby'
'ddd', 111, '06/01/08'
'dsad', 111 , '06/01/08'
the statement
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"SELECT * FROM active_consults WHERE mrn LIKE '$mrnstring' or patient_name LIKE '$patientstring' or fellow LIKE '$fellowstring'"
the variable settings
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$mrnstring = 111;
$patientstring = "";
$fellowstring = "";
return values
-------------------------
'ddd', 111, '06/01/08'
'dsad', 111 , '06/01/08'
the variable settings
------------------------
$mrnstring = 111;
$patientstring = "smnith";
$fellowstring = "";
return values
------------------
'smnith', 12345, '06/01/08'
'ddd', 111, '06/01/08'
'dsad', 111 , '06/01/08'