oracle - 执行立即绑定变量

Question

我有以下计算表格内容的函数，但是当我传递任何参数时，它会抛出：

EXEC DBMS_OUTPUT.PUT_LINE(get_size('employees'))
Error report -
ORA-00903: invalid table name
ORA-06512: at "HR.GET_SIZE", line 5
ORA-06512: at line 1
00903. 00000 -  "invalid table name"

功能

CREATE OR REPLACE FUNCTION get_size(v_table_name IN VARCHAR2) 
   RETURN NUMBER IS total_size NUMBER(16);
   plsql_statement VARCHAR2(500) := 'SELECT COUNT(*) FROM  :param';
BEGIN
    EXECUTE IMMEDIATE plsql_statement INTO total_size USING v_table_name;
    RETURN(total_size); 
END;
/


EXEC DBMS_OUTPUT.PUT_LINE(get_size('employees'));

Answer 1

你不能绑定表名，它需要被构造。

CREATE OR REPLACE FUNCTION get_size(v_table_name IN VARCHAR2) 
   RETURN NUMBER IS total_size NUMBER(16);
   plsql_statement VARCHAR2(500)
BEGIN
    plsql_statement := 'SELECT COUNT(*) FROM  ' || v_table_name;
    EXECUTE IMMEDIATE plsql_statement INTO total_size;
    RETURN(total_size); 
END;
/


EXEC DBMS_OUTPUT.PUT_LINE(get_size('employees'));

Answer 2

您不能绑定表名或列名。您只能绑定变量。

在您的情况下，您只需要立即执行动态 SQL。

SQL> CREATE OR REPLACE FUNCTION get_size(v_table_name IN VARCHAR2)
  2     RETURN NUMBER IS total_size NUMBER(16);
  3     plsql_statement VARCHAR2(500);
  4  BEGIN
  5      plsql_statement := 'SELECT COUNT(*) FROM  ' || v_table_name;
  6      EXECUTE IMMEDIATE plsql_statement INTO total_size;
  7      RETURN(total_size);
  8  END;
  9  /

Function created.

SQL>
SQL>
SQL> EXEC DBMS_OUTPUT.PUT_LINE(get_size('EMP'));
14

PL/SQL procedure successfully completed.

SQL>