So far, still no luck.

I've tried with quotes and without quotes around the values to be passed. I've tried specifying the data type when I bind the parameter.

Thanks to Cine for reminding me to check the DEBUGGING section. I did find the trace method useful. After reading that, I thought that it was the wrong data type being passed, but I didn't have any success when specifying the data type.

The query does return rows when I run it manually from SQLPlus.

There wasn't any documentation of the trace output that I could find, but it looks like it's using the correct value for the replaceable parameter, then returning 0 rows, judging by the "0E0" status of the execute.

If anyone can discern anything from the following, I would be grateful, but I think I'll have to re-prepare the statement for each value.

Here's some of the output generated using the trace method...

    dbd_preparse scanned 1 distinct placeholders
    fbh 1: 'ACCOUNT_NO'    NO null , otype   2->  5, dbsize 22/40, p10
+.s0
      out: ftype 5, bufl 41. indp 0, rlen 0, rcode 0
    fbh 2: 'EXTERNAL_ID'    NO null , otype  96->  5, dbsize 48/48, p4
+8.s0
      out: ftype 5, bufl 49. indp 0, rlen 0, rcode 0
    fbh 3: 'BILL_REF_NO'    NULLable, otype  96->  5, dbsize 1/1, p1.s
+0
      out: ftype 5, bufl 2. indp 0, rlen 0, rcode 0
    fbh 4: 'BILL_COMPANY'    NULLable, otype   1->  5, dbsize 56/56, p
+56.s0
      out: ftype 5, bufl 57. indp 0, rlen 0, rcode 0
    fbh 5: 'BILL_PERIOD'    NULLable, otype  96->  5, dbsize 3/3, p3.s
+0
      out: ftype 5, bufl 4. indp 0, rlen 0, rcode 0
    fbh 6: 'STATEMENT_DATE'    NULLable, otype  12->  5, dbsize 7/75, 
+p0.s0
      out: ftype 5, bufl 76. indp 0, rlen 0, rcode 0
    <- prepare= DBI::st=HASH(0x1b4afc) at paramtest.pl line 57.
    -> quote in DBD::_::db for DBD::Oracle::db (DBI::db=HASH(0x24bdb8)
+~0x1b4aa8 '118554')
    <- quote= ( ''118554'' ) [1 items] at paramtest.pl line 83.
    -> execute for DBD::Oracle::st (DBI::st=HASH(0x1b4afc)~0x27b014 ''
+118554'')
       bind :p1 <== ''118554'' (type 0)
       bind :p1 <== ''118554'' (size 8/9/0, ptype 4, otype 1)
    dbd_st_execute (for sql f4 after oci f62, out0)...
    dbd_st_execute complete (rc1403, w00, rpc0, eod1403, out0)
    <- execute= '0E0' at paramtest.pl line 83.
    -> fetchrow_array for DBD::Oracle::st (DBI::st=HASH(0x1b4afc)~0x27
+b014)
    <- fetchrow_array= ( ) [0 items] at paramtest.pl line 85.
    -> quote for DBD::Oracle::db (DBI::db=HASH(0x24bdb8)~0x1b4aa8 '118
+555')
    <- quote= ( ''118555'' ) [1 items] at paramtest.pl line 83.
    -> execute for DBD::Oracle::st (DBI::st=HASH(0x1b4afc)~0x27b014 ''
+118555'')
       bind :p1 <== ''118555'' (type 0)
       bind :p1 <== ''118555'' (size 8/9/0, ptype 4, otype 1)
    dbd_st_execute (for sql f4 after oci f62, out0)...
    dbd_st_execute complete (rc1403, w00, rpc0, eod1403, out0)
    <- execute= '0E0' at paramtest.pl line 83.
    -> fetchrow_array for DBD::Oracle::st (DBI::st=HASH(0x1b4afc)~0x27
+b014)
    <- fetchrow_array= ( ) [0 items] at paramtest.pl line 85.
    -> quote for DBD::Oracle::db (DBI::db=HASH(0x24bdb8)~0x1b4aa8 '118
+528')
    <- quote= ( ''118528'' ) [1 items] at paramtest.pl line 83.
    -> execute for DBD::Oracle::st (DBI::st=HASH(0x1b4afc)~0x27b014 ''
+118528'')
       bind :p1 <== ''118528'' (type 0)
       bind :p1 <== ''118528'' (size 8/9/0, ptype 4, otype 1)
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