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; /
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