MySql CASE statement in an UPDATE query

Question

I have a problem in getting the values from Table A and updating to Table B with a CASE Statement. My CASE Statement is as follows. I guess there is an syntax error:

$strSQLInsert2 = "UPDATE commercial_acc_cust SET pbg_curr =  
CASE WHEN ('".$values["main_section"]."'='Bank Guarantee PBG') Then 'pbg_curr' 
END 
WHERE tender_id=" . $values["tender_id"];

Answer 1

if($values["main_section"] == 'Bank Guarantee PBG'){    
    $strSQLInsert2 = "UPDATE commercial_acc_cust SET pbg_curr = 'pbg_curr' 
    WHERE tender_id=" . $values["tender_id"];
}