根据列和表列表获取要删除的记录列表

Question

我有一张桌子

Employees

:

员工ID	员工矩阵
1	XCV
2	香港天文台

我有一个

EmployeeMatricule

列表，我需要用它来从表

Employees

中删除记录，以及与其相关的表，其中一个列名称为

EmployeeId

。

查找具有 EmployeeId 列的表：

 SELECT table_name
        FROM all_tab_columns
        WHERE column_name = 'EmployeeId' AND table_name <> 'Employees'

作为上述查询的结果，我将这些表作为输出

• 员工部门
• 薪资待遇
• 薪资薪资

假设这是我的 EmployeeMatricule 列表：XCV、HKO、MXP

所以我想要每个表 EmployeeDepartment/SalaryPackage/SalaryPayroll :

SELECT *
FROM EmployeeDepartment
WHERE EmployeeId IN (
    SELECT DISTINCT EmployeeId
    FROM Employees
    WHERE EmployeeMatricule IN ('XCV', 'HKO', 'MXP'))

SalaryPackage 和 SalaryPayroll 的查询相同。

我尝试使用光标：

DECLARE
    CURSOR table_cursor IS
        SELECT table_name
        FROM all_tab_columns
        WHERE column_name = 'EmployeeId' AND table_name <> 'Employees'; 

    v_table_name VARCHAR2(128);
    v_sql VARCHAR2(4000);
    EmployeeId Employees.EmployeeId%TYPE;
BEGIN
    OPEN table_cursor; 

    LOOP
        FETCH table_cursor INTO v_table_name; 

        EXIT WHEN table_cursor%NOTFOUND; 

        v_sql := 'SELECT EmployeeId FROM ' || v_table_name ||
                 ' WHERE EmployeeId IN (SELECT DISTINCT EmployeeId FROM employee WHERE EmployeeMatricule IN (''XCV'', ''HKO'', ''MXP''))';

        DBMS_OUTPUT.PUT_LINE('Executing SELECT on table: ' || v_table_name);

        FOR rec IN (EXECUTE IMMEDIATE v_sql)
        LOOP
            DBMS_OUTPUT.PUT_LINE('EmployeeId: ' || rec.EmployeeId);
        END LOOP;
    END LOOP;

    CLOSE table_cursor; 
END;

我当前的输出是：

在表 : EmployeeDepartment 上执行 SELECT

在表上执行 SELECT：SalaryPackage

在表上执行 SELECT：SalaryPayroll

虽然我希望返回带有 EmployeeId 的行来删除。

Answer 1

具体方法如下。

先看样本数据：

SQL> select table_name from user_tab_columns
  2  where column_name = 'EMPLOYEEID'
  3    and table_name <> 'EMPLOYEES';

TABLE_NAME
--------------------------------------------------------------------------------
EMPLOYEEDEPARTMENT
SALARYPAYROLL

SQL> select * from employeedepartment
  2  where employeeid in (select employeeid from employees
  3                       where employeematricule in ('XCV', 'HKO', 'MXP'));

EMPLOYEEID DEPTID
---------- ------
         1 Dept 1
         2 Dept 2

SQL> select * From salarypayroll;

EMPLOYEEID PAYROLL
---------- ---------
         2 Payroll A

SQL>

在一个过程中，您确实需要动态 SQL（因为您不知道实际使用的表名称），但您不需要

execute immediate

它来显示数据；我建议改用 refcursor。另一方面，当从这些表中删除行时，您确实需要它。

SQL> set serveroutput on;
SQL> declare
  2    rc sys_refcursor;
  3    l_empid employees.employeeid%type;
  4  begin
  5    for cur_t in (select table_name
  6                  from user_tab_columns
  7                  where column_name = 'EMPLOYEEID'
  8                    and table_name <> 'EMPLOYEES'
  9                 )
 10    loop
 11      open rc for 'select employeeid from ' || cur_t.table_name ||
 12                  ' where employeeid in (select employeeid from employees' ||
 13                  q'[                      where employeematricule in ('XCV', 'HKO', 'MXP'))]';
 14      loop
 15        fetch rc into l_empid;
 16        exit when rc%notfound;
 17        dbms_output.put_line('Employee ID = ' || l_empid);
 18
 19        execute immediate 'delete from ' || cur_t.table_name || ' where employeeid = ' || l_empid;
 20      end loop;
 21    end loop;
 22  end;
 23  /

结果是

Employee ID = 1
Employee ID = 2
Employee ID = 2

PL/SQL procedure successfully completed.

数据呢？在与

employees

不同的表中删除：

SQL> select * from employees;

EMPLOYEEID EMP
---------- ---
         1 XCV
         2 HKO

SQL> select * From employeedepartment;

no rows selected

SQL> select * from salarypayroll;

no rows selected

SQL>