执行execute immediate为何错误是缺少右括号?
sqlstr varchar2(2000);
a varchar2(2000);
b varchar2(2000);
sqlstr := 'select decode(sch_h' || to_char(to_char(dat,'dd') - 6,'00') ||',''F'',1,0)' ||
' ,decode(sch_h' || to_char(to_char(dat,'dd') - 5,'00') ||',''F'',1,0)' ||
' from att_shfcal where sch_emp = ''' || workno || ''' and sch_mon = ''' || tomon ||'''';
execute immediate sqlstr into a,b;
请问为何总是报错,"少右括号"