PHP - Como obtener el valor de un LVARCHAR

Description:
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how can get lvarchar value from table

Reproduce code:
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$con = ifx_connect(ID,USER,PASSWORD);
ifx_textasvarchar(0);
// u_address is lvarchar type
$stmt = ifx_prepare("Select u_address from customer",$con);
ifx_do($stmt);
$row=ifx_fetch_row($stmt);
$u_address = $row["u_address"];


Expected result:
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$u_address="111 tonducthang"

Actual result:
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ESQL/C : u_address : unsupported field type[0]