Oracle的动态SQL

例1：传递表名，和Where条件删除数据

CREATE OR REPLACE PROCEDURE raise_emp_salary (column_value NUMBER, 
                             emp_column VARCHAR2, amount NUMBER) IS
   v_column VARCHAR2(30);
   sql_stmt  VARCHAR2(200);
BEGIN
-- determine if a valid column name has been given as input
  SELECT COLUMN_NAME INTO v_column FROM USER_TAB_COLS 
    WHERE TABLE_NAME = 'EMPLOYEES' AND COLUMN_NAME = emp_column;
  sql_stmt := 'UPDATE employees SET salary = salary + :1 WHERE ' 
               || v_column || ' = :2';
  EXECUTE IMMEDIATE sql_stmt USING amount, column_value;
  IF SQL%ROWCOUNT > 0 THEN
    DBMS_OUTPUT.PUT_LINE('Salaries have been updated for: ' || emp_column 
                        || ' = ' || column_value);
  END IF;
  EXCEPTION
  WHEN NO_DATA_FOUND THEN
    DBMS_OUTPUT.PUT_LINE ('Invalid Column: ' || emp_column);
END raise_emp_salary;
/

DECLARE
   plsql_block       VARCHAR2(500);
BEGIN
-- note the semi-colons (;) inside the quotes '...'
  plsql_block := 'BEGIN raise_emp_salary(:cvalue, :cname, :amt); END;';
  EXECUTE IMMEDIATE plsql_block USING 110, 'DEPARTMENT_ID', 10;
  EXECUTE IMMEDIATE 'BEGIN raise_emp_salary(:cvalue, :cname, :amt); END;'
      USING 112, 'EMPLOYEE_ID', 10;
END;
/

DECLARE
   sql_stmt          VARCHAR2(200);
   v_column          VARCHAR2(30) := 'DEPARTMENT_ID';
   dept_id           NUMBER(4) := 46;
   dept_name         VARCHAR2(30) := 'Special Projects';
   mgr_id            NUMBER(6) := 200;
   loc_id            NUMBER(4) := 1700;
BEGIN
-- note that there is no semi-colon (;) inside the quotes '...'
  EXECUTE IMMEDIATE 'CREATE TABLE bonus (id NUMBER, amt NUMBER)';
  sql_stmt := 'INSERT INTO departments VALUES (:1, :2, :3, :4)';
  EXECUTE IMMEDIATE sql_stmt USING dept_id, dept_name, mgr_id, loc_id;
  EXECUTE IMMEDIATE 'DELETE FROM departments WHERE ' || v_column || ' = :num'
      USING dept_id;
  EXECUTE IMMEDIATE 'ALTER SESSION SET SQL_TRACE TRUE';
  EXECUTE IMMEDIATE 'DROP TABLE bonus';
END;
/

例2 动态的表名和Where语句

CREATE TABLE employees_temp AS SELECT * FROM employees;

CREATE OR REPLACE PROCEDURE delete_rows (
   table_name IN VARCHAR2,
   condition  IN VARCHAR2 DEFAULT NULL) AS
   where_clause  VARCHAR2(100) := ' WHERE ' || condition;
   v_table      VARCHAR2(30);
BEGIN
-- first make sure that the table actually exists; if not, raise an exception
  SELECT OBJECT_NAME INTO v_table FROM USER_OBJECTS
    WHERE OBJECT_NAME = UPPER(table_name) AND OBJECT_TYPE = 'TABLE';
   IF condition IS NULL THEN where_clause := NULL; END IF;
   EXECUTE IMMEDIATE 'DELETE FROM ' || v_table || where_clause;
  EXCEPTION
  WHEN NO_DATA_FOUND THEN
    DBMS_OUTPUT.PUT_LINE ('Invalid table: ' || table_name);
END;
/
BEGIN
  delete_rows('employees_temp', 'employee_id = 111');
END;
/

例3 替换IN和OUT参数

DECLARE
   plsql_block VARCHAR2(500);
   new_deptid  NUMBER(4);
   new_dname   VARCHAR2(30) := 'Advertising';
   new_mgrid   NUMBER(6) := 200;
   new_locid   NUMBER(4) := 1700;
BEGIN
   plsql_block := 'BEGIN create_dept(:a, :b, :c, :d); END;';
   EXECUTE IMMEDIATE plsql_block
      USING IN OUT new_deptid, new_dname, new_mgrid, new_locid;
END;
/

例4 使用BULK COLLECT INTO的动态SQL

DECLARE
   TYPE EmpCurTyp IS REF CURSOR;
   TYPE NumList IS TABLE OF NUMBER;
   TYPE NameList IS TABLE OF VARCHAR2(25);
   emp_cv EmpCurTyp;
   empids NumList;
   enames NameList;
   sals   NumList;
BEGIN
   OPEN emp_cv FOR 'SELECT employee_id, last_name FROM employees';
   FETCH emp_cv BULK COLLECT INTO empids, enames;
   CLOSE emp_cv;
   EXECUTE IMMEDIATE 'SELECT salary FROM employees'
      BULK COLLECT INTO sals;
END;
/

例5 使用RETURNING BULK COLLECT INTO的动态SQL

DECLARE
   TYPE NameList IS TABLE OF VARCHAR2(15);
   enames    NameList;
   bonus_amt NUMBER := 50;
   sql_stmt  VARCHAR(200);
BEGIN
   sql_stmt := 'UPDATE employees SET salary = salary + :1 
                RETURNING last_name INTO :2';
   EXECUTE IMMEDIATE sql_stmt
      USING bonus_amt RETURNING BULK COLLECT INTO enames;
END;
/

例6 FORALL中的动态SQL

DECLARE
   TYPE NumList IS TABLE OF NUMBER;
   TYPE NameList IS TABLE OF VARCHAR2(15);
   empids NumList;
   enames NameList;
BEGIN
   empids := NumList(101,102,103,104,105);
   FORALL i IN 1..5
      EXECUTE IMMEDIATE
        'UPDATE employees SET salary = salary * 1.04 WHERE employee_id = :1
         RETURNING last_name INTO :2'
         USING empids(i) RETURNING BULK COLLECT INTO enames;
END;
/

例7 在动态SQL中重复使用Placeholder

CREATE PROCEDURE calc_stats(w NUMBER, x NUMBER, y NUMBER, z NUMBER) IS
BEGIN
  DBMS_OUTPUT.PUT_LINE(w + x + y + z);
END;
/
DECLARE
   a NUMBER := 4;
   b NUMBER := 7;
   plsql_block VARCHAR2(100);
BEGIN
   plsql_block := 'BEGIN calc_stats(:x, :x, :y, :x); END;';
   EXECUTE IMMEDIATE plsql_block USING a, b;
END;
/

例8 对%ROWCOUNT的访问

DECLARE
  TYPE cursor_ref IS REF CURSOR;
  c1 cursor_ref;
  TYPE emp_tab IS TABLE OF employees%ROWTYPE;
  rec_tab emp_tab;
  rows_fetched NUMBER;
BEGIN
  OPEN c1 FOR 'SELECT * FROM employees';
  FETCH c1 BULK COLLECT INTO rec_tab;
  rows_fetched := c1%ROWCOUNT;
  DBMS_OUTPUT.PUT_LINE('Number of employees fetched: ' || TO_CHAR(rows_fetched));
END;
/

例9 对数据集的动态Fetch

DECLARE
   TYPE EmpCurTyp IS REF CURSOR;
   emp_cv   EmpCurTyp;
   emp_rec  employees%ROWTYPE;
   sql_stmt VARCHAR2(200);
   v_job   VARCHAR2(10) := 'ST_CLERK';
BEGIN
   sql_stmt := 'SELECT * FROM employees WHERE job_id = :j';
   OPEN emp_cv FOR sql_stmt USING v_job;
   LOOP
     FETCH emp_cv INTO emp_rec;
     EXIT WHEN emp_cv%NOTFOUND;
     DBMS_OUTPUT.PUT_LINE('Name: ' || emp_rec.last_name || ' Job Id: ' ||
                           emp_rec.job_id);
   END LOOP;
   CLOSE emp_cv;
END;
/