sql里的引号处理

今天开发问我：

为什么编译过不去，一看就知道是缺少引号，应该改成

 

set serveroutput on
declare
abc VARCHAR2(2000);
begin
TIME_D := 'select (sysdate - 8 / 24 - to_date('||CHR(39)||'1970-01-01'||CHR(39)||', '||CHR(39)||'yyyy-mm-dd'||CHR(39)||')) * 86400000 from dual';
dbms_output.put_line(abc);
end;

 

 

原来语句格式：

 

 

CREATE OR REPLACE TRIGGER tttest
after INSERT
ON test
REFERENCING NEW AS New OLD AS Old
FOR EACH ROW
DECLARE
TIME_D varchar2(30);
BEGIN
  
   TIME_D := select (sysdate - 8 / 24 - to_date('1970-01-01', 'yyyy-mm-dd')) * 86400000 from dual;
  
END ;