将一个表clob中某一内容更新到另一表clob

update hb_wssb_busi_formdata f
   set f.formdata = replace(f.formdata,
                            '"usertype"',
                            '"itemid":' ||
                            (select json_value(t.busidata, '$.itemid')
                               from hb_wssb_busi_data t
                              where t.bsnum = f.bsnum
                                and t.sfbj = '0') || ',"usertype"')
 where f.bsnum = '72577330X2018081314030600001T'