Oracle

需求：举个例子，oracle测试库的scott用户下面的有张emp表，emp表的ename列中有一行数据为'CLARK'。红色标记部分。

SQL> select * from scott.emp;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81          1        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

可是你忘记了'CLARK'这个字符在哪张表里了，如何找出来？

下面是plsql代码

set serveroutput on
declare
  v_sql varchar2(2000);
  v_count number;
begin
  for cur in(select t.owner, t.table_name, t.column_name from dba_tab_columns t where t.owner = 'SCOTT') 
    loop
      begin v_sql := 'select count(1) from ' || cur.owner || '.' || cur.table_name || ' where ' || cur.column_name || ' like ''%CLARK%'''; 
      execute immediate v_sql into v_count;
      if(v_count >= 1) then
        dbms_output.put_line(cur.owner || ':' || cur.table_name || ':' || cur.column_name);
      end if;
      exception
        when others then
          null;
      end;
    end loop;
end;    
/

说明：
# 如果你不确定表是哪个用户的，就把where t.owner = 'SCOTT'去掉进行全库搜索，但是效率会很低
# 在plsqldeveloper command window中执行上面代码
结果就是CLARK出现在scott用户下的emp表的ename列中