【Oracle】DML语言

个人主页：Guiat
归属专栏：Oracle

正文
DML（Data Manipulation Language）是Oracle数据库的"魔法师"，专门负责数据的增删改查操作。如果说DDL是建房子的，那DML就是在房子里生活的——添置家具、整理物品、搬家换房。它让静态的数据结构变得生动起来，是我们与数据库数据打交道最频繁的语言！

1. DML概述

1.1 什么是DML？

DML就像是数据库的"生活管家"，负责管理数据库中的实际数据。它不改变数据库的结构，而是专注于数据内容的操作。在Oracle这个数据王国里，DML是让数据"活"起来的关键工具。

1.2 DML的核心功能

Oracle DML的功能体系就像一个完整的数据处理工厂：

2. INSERT语句详解

2.1 基础插入操作

INSERT就像往盒子里放东西，有很多种放法：

-- 最基本的插入
INSERT INTO employees (employee_id, first_name, last_name, email, hire_date)
VALUES (1001, 'John', 'Doe', '[e-mail]', SYSDATE);-- 插入所有列（按表结构顺序）
INSERT INTO employees
VALUES (1002, 'Jane', 'Smith', '[e-mail]', '555-1234', SYSDATE, 'IT_PROG', 5000, NULL, 100, 20);-- 插入部分列（其他列使用默认值或NULL）
INSERT INTO employees (employee_id, first_name, last_name, email)
VALUES (1003, 'Bob', 'Johnson', '[e-mail]');-- 使用序列插入
INSERT INTO employees (employee_id, first_name, last_name, email, hire_date)
VALUES (emp_seq.NEXTVAL, 'Alice', 'Brown', '[e-mail]', SYSDATE);-- 插入计算值
INSERT INTO order_summary (order_id, order_date, total_amount, tax_amount, final_amount)
VALUES (1001, SYSDATE, 1000, 1000 * 0.08, 1000 * 1.08);-- 插入函数结果
INSERT INTO audit_log (log_id, table_name, action_type, action_date, username)
VALUES (audit_seq.NEXTVAL, 'EMPLOYEES', 'INSERT', SYSTIMESTAMP, USER);

2.2 子查询插入

用子查询插入就像批量搬家，一次性处理大量数据：

-- 从其他表插入数据
INSERT INTO employees_backup
SELECT * FROM employees WHERE department_id = 20;-- 插入聚合数据
INSERT INTO department_summary (dept_id, dept_name, emp_count, avg_salary, total_salary)
SELECT d.department_id,d.department_name,COUNT(e.employee_id),AVG(e.salary),SUM(e.salary)
FROM departments d
LEFT JOIN employees e ON d.department_id = e.department_id
GROUP BY d.department_id, d.department_name;-- 插入复杂计算结果
INSERT INTO sales_analysis (region, year, month, total_sales, growth_rate)
SELECT region,EXTRACT(YEAR FROM sale_date) as year,EXTRACT(MONTH FROM sale_date) as month,SUM(amount) as total_sales,ROUND((SUM(amount) - LAG(SUM(amount)) OVER (PARTITION BY region ORDER BY EXTRACT(YEAR FROM sale_date), EXTRACT(MONTH FROM sale_date))) / LAG(SUM(amount)) OVER (PARTITION BY region ORDER BY EXTRACT(YEAR FROM sale_date), EXTRACT(MONTH FROM sale_date)) * 100, 2) as growth_rate
FROM sales_data
GROUP BY region, EXTRACT(YEAR FROM sale_date), EXTRACT(MONTH FROM sale_date);-- 条件插入
INSERT INTO high_performers (employee_id, performance_score, bonus_eligible)
SELECT employee_id,(salary * 0.1 + COALESCE(commission_pct * salary, 0)) as performance_score,CASE WHEN salary > 8000 THEN 'Y' ELSE 'N' END
FROM employees
WHERE hire_date < ADD_MONTHS(SYSDATE, -12)AND department_id IN (10, 20, 30);

2.3 多表插入

Oracle的多表插入功能就像是"一箭多雕"，一次操作影响多个表：

-- 无条件多表插入
INSERT ALLINTO sales_summary (region, total_amount) VALUES (region, amount)INTO sales_detail (sale_id, customer_id, amount) VALUES (sale_id, customer_id, amount)INTO sales_audit (sale_id, insert_date) VALUES (sale_id, SYSDATE)
SELECT sale_id, region, customer_id, amount
FROM sales_data
WHERE sale_date = TRUNC(SYSDATE);-- 条件多表插入
INSERT ALLWHEN amount > 10000 THENINTO high_value_sales (sale_id, amount, customer_id) VALUES (sale_id, amount, customer_id)WHEN amount BETWEEN 1000 AND 10000 THENINTO medium_value_sales (sale_id, amount, customer_id) VALUES (sale_id, amount, customer_id)ELSEINTO low_value_sales (sale_id, amount, customer_id) VALUES (sale_id, amount, customer_id)
SELECT sale_id, amount, customer_id
FROM sales_data
WHERE sale_date >= TRUNC(SYSDATE);-- 旋转插入（数据透视）
INSERT ALLINTO quarterly_sales (year, quarter, region, amount) VALUES (year, 1, region, q1_sales)INTO quarterly_sales (year, quarter, region, amount) VALUES (year, 2, region, q2_sales)INTO quarterly_sales (year, quarter, region, amount) VALUES (year, 3, region, q3_sales)INTO quarterly_sales (year, quarter, region, amount) VALUES (year, 4, region, q4_sales)
SELECT year, region, q1_sales, q2_sales, q3_sales, q4_sales
FROM annual_sales_pivot;-- 复杂的条件多表插入
INSERT ALLWHEN department_id = 10 THENINTO dept_10_employees (employee_id, name, salary) VALUES (employee_id, first_name || ' ' || last_name, salary)INTO dept_10_salaries (employee_id, salary, bonus) VALUES (employee_id, salary, salary * 0.1)WHEN department_id = 20 THENINTO dept_20_employees (employee_id, name, salary) VALUES (employee_id, first_name || ' ' || last_name, salary)WHEN salary > 5000 THENINTO high_earners (employee_id, salary, department_id) VALUES (employee_id, salary, department_id)
SELECT employee_id, first_name, last_name, salary, department_id
FROM employees
WHERE status = 'ACTIVE';

2.4 批量插入优化

批量插入就像是用卡车运货，比一件件搬要高效得多：

-- 使用FORALL进行批量插入（PL/SQL）
DECLARETYPE emp_array IS TABLE OF employees%ROWTYPE;l_employees emp_array;
BEGIN-- 准备数据l_employees := emp_array();FOR i IN 1..10000 LOOPl_employees.EXTEND;l_employees(i).employee_id := emp_seq.NEXTVAL;l_employees(i).first_name := 'Employee' || i;l_employees(i).last_name := 'Test';l_employees(i).email := 'emp' || i || '@test.com';l_employees(i).hire_date := SYSDATE;l_employees(i).job_id := 'IT_PROG';l_employees(i).salary := 5000 + MOD(i, 3000);END LOOP;-- 批量插入FORALL i IN l_employees.FIRST..l_employees.LASTINSERT INTO employees VALUES l_employees(i);COMMIT;DBMS_OUTPUT.PUT_LINE('Inserted ' || l_employees.COUNT || ' employees');
END;
/-- 使用INSERT /*+ APPEND */ 提高性能
INSERT /*+ APPEND */ INTO employees_archive
SELECT * FROM employees WHERE hire_date < DATE '2020-01-01';-- 并行插入
ALTER SESSION ENABLE PARALLEL DML;
INSERT /*+ PARALLEL(employees_archive, 4) */ INTO employees_archive
SELECT * FROM employees WHERE department_id IN (10, 20, 30);-- 使用NOLOGGING减少日志
ALTER TABLE employees_temp NOLOGGING;
INSERT /*+ APPEND NOLOGGING */ INTO employees_temp
SELECT * FROM external_employee_data;
ALTER TABLE employees_temp LOGGING;

3. UPDATE语句详解

3.1 基础更新操作

UPDATE就像是重新装修房间，可以改变现有的数据：

-- 简单更新
UPDATE employees 
SET salary = 6000 
WHERE employee_id = 1001;-- 更新多个字段
UPDATE employees 
SET salary = salary * 1.1,commission_pct = 0.05,modified_date = SYSDATE
WHERE department_id = 20;-- 使用表达式更新
UPDATE employees 
SET salary = CASE WHEN job_id = 'IT_PROG' THEN salary * 1.15WHEN job_id = 'SA_REP' THEN salary * 1.10WHEN job_id = 'ST_CLERK' THEN salary * 1.05ELSE salary * 1.03
END,
email = LOWER(first_name || '.' || last_name || '@company.com')
WHERE hire_date < ADD_MONTHS(SYSDATE, -12);-- 使用函数更新
UPDATE products 
SET product_name = INITCAP(product_name),description = REGEXP_REPLACE(description, '\s+', ' '),modified_date = SYSTIMESTAMP
WHERE category_id = 5;-- 条件更新
UPDATE orders 
SET status = 'SHIPPED',shipped_date = SYSDATE,tracking_number = 'TRK' || LPAD(order_id, 10, '0')
WHERE status = 'PROCESSING' AND order_date < SYSDATE - 2;

3.2 关联更新

关联更新就像是根据其他房间的情况来调整当前房间：

-- 使用子查询更新
UPDATE employees e
SET salary = (SELECT AVG(salary) * 1.1FROM employees WHERE department_id = e.department_id
)
WHERE job_id = 'IT_PROG';-- 多列子查询更新
UPDATE employees e
SET (salary, commission_pct) = (SELECT j.max_salary * 0.8, 0.1FROM jobs jWHERE j.job_id = e.job_id
)
WHERE hire_date > ADD_MONTHS(SYSDATE, -6);-- 使用EXISTS的关联更新
UPDATE products p
SET discontinued = 'Y'
WHERE NOT EXISTS (SELECT 1 FROM order_details od WHERE od.product_id = p.product_id AND od.order_date > ADD_MONTHS(SYSDATE, -12)
);-- 复杂关联更新
UPDATE customers c
SET (credit_limit, customer_status) = (SELECT CASE WHEN total_orders > 100 THEN 50000WHEN total_orders > 50 THEN 25000WHEN total_orders > 10 THEN 10000ELSE 5000END,CASE WHEN total_orders > 50 THEN 'VIP'WHEN total_orders > 10 THEN 'REGULAR'ELSE 'NEW'ENDFROM (SELECT customer_id,COUNT(*) as total_orders,SUM(total_amount) as total_spentFROM ordersWHERE order_date > ADD_MONTHS(SYSDATE, -12)GROUP BY customer_id) order_statsWHERE order_stats.customer_id = c.customer_id
)
WHERE EXISTS (SELECT 1 FROM orders o WHERE o.customer_id = c.customer_id
);

3.3 批量更新优化

-- 使用MERGE进行高效更新
MERGE INTO employees e
USING (SELECT employee_id, salary * 1.1 as new_salaryFROM employeesWHERE performance_rating = 'EXCELLENT'
) perf
ON (e.employee_id = perf.employee_id)
WHEN MATCHED THENUPDATE SET salary = perf.new_salary,last_raise_date = SYSDATE;-- 分批更新大表
DECLAREv_batch_size NUMBER := 10000;v_total_updated NUMBER := 0;v_batch_updated NUMBER;
BEGINLOOPUPDATE employees SET status = 'INACTIVE'WHERE status = 'TEMP' AND hire_date < ADD_MONTHS(SYSDATE, -24)AND ROWNUM <= v_batch_size;v_batch_updated := SQL%ROWCOUNT;v_total_updated := v_total_updated + v_batch_updated;COMMIT;EXIT WHEN v_batch_updated = 0;DBMS_OUTPUT.PUT_LINE('Updated ' || v_batch_updated || ' rows');END LOOP;DBMS_OUTPUT.PUT_LINE('Total updated: ' || v_total_updated || ' rows');
END;
/-- 并行更新
ALTER SESSION ENABLE PARALLEL DML;
UPDATE /*+ PARALLEL(employees, 4) */ employees
SET salary = salary * 1.05
WHERE department_id IN (10, 20, 30, 40);
COMMIT;

4. DELETE语句详解

4.1 基础删除操作

DELETE就像是清理房间，移除不需要的物品：

-- 简单删除
DELETE FROM employees WHERE employee_id = 1001;-- 条件删除
DELETE FROM employees 
WHERE status = 'TERMINATED' AND termination_date < ADD_MONTHS(SYSDATE, -24);-- 使用子查询删除
DELETE FROM order_details
WHERE order_id IN (SELECT order_id FROM orders WHERE order_date < ADD_MONTHS(SYSDATE, -36)AND status = 'CANCELLED'
);-- 使用EXISTS删除
DELETE FROM products p
WHERE EXISTS (SELECT 1 FROM discontinued_products dp WHERE dp.product_id = p.product_id
);-- 复杂条件删除
DELETE FROM sales_data
WHERE sale_date < ADD_MONTHS(SYSDATE, -60)AND customer_id NOT IN (SELECT DISTINCT customer_id FROM orders WHERE order_date > ADD_MONTHS(SYSDATE, -12))AND amount < 100;

4.2 关联删除

-- 删除孤儿记录
DELETE FROM order_details od
WHERE NOT EXISTS (SELECT 1 FROM orders o WHERE o.order_id = od.order_id
);-- 基于统计信息删除
DELETE FROM customers c
WHERE customer_id NOT IN (SELECT DISTINCT customer_id FROM orders WHERE order_date > ADD_MONTHS(SYSDATE, -36)
)
AND created_date < ADD_MONTHS(SYSDATE, -48);-- 删除重复数据（保留最新的）
DELETE FROM employees e1
WHERE e1.rowid > (SELECT MIN(e2.rowid)FROM employees e2WHERE e2.email = e1.email
);-- 或者使用分析函数删除重复数据
DELETE FROM (SELECT rowid, ROW_NUMBER() OVER (PARTITION BY email ORDER BY hire_date DESC, employee_id DESC) as rnFROM employees
)
WHERE rn > 1;

4.3 批量删除优化

-- 分批删除避免锁表
DECLAREv_batch_size NUMBER := 5000;v_total_deleted NUMBER := 0;v_batch_deleted NUMBER;
BEGINLOOPDELETE FROM audit_log WHERE log_date < ADD_MONTHS(SYSDATE, -12)AND ROWNUM <= v_batch_size;v_batch_deleted := SQL%ROWCOUNT;v_total_deleted := v_total_deleted + v_batch_deleted;COMMIT;EXIT WHEN v_batch_deleted = 0;-- 给其他会话一些处理时间DBMS_LOCK.SLEEP(0.1);DBMS_OUTPUT.PUT_LINE('Deleted ' || v_batch_deleted || ' rows');END LOOP;DBMS_OUTPUT.PUT_LINE('Total deleted: ' || v_total_deleted || ' rows');
END;
/-- 使用TRUNCATE快速清空表（注意：不能回滚）
TRUNCATE TABLE temp_calculations;-- 删除分区数据
ALTER TABLE sales_data DROP PARTITION sales_2020_q1;-- 并行删除
ALTER SESSION ENABLE PARALLEL DML;
DELETE /*+ PARALLEL(old_transactions, 4) */ FROM old_transactions
WHERE transaction_date < ADD_MONTHS(SYSDATE, -84);
COMMIT;

5. MERGE语句详解

5.1 MERGE基础语法

MERGE就像是"智能搬家"，能够根据情况决定是搬新家具还是更新现有家具：

-- 基本MERGE语法
MERGE INTO employees e
USING employee_updates eu
ON (e.employee_id = eu.employee_id)
WHEN MATCHED THENUPDATE SET salary = eu.new_salary,department_id = eu.new_department_id,modified_date = SYSDATE
WHEN NOT MATCHED THENINSERT (employee_id, first_name, last_name, email, hire_date, salary, department_id)VALUES (eu.employee_id, eu.first_name, eu.last_name, eu.email, SYSDATE, eu.new_salary, eu.new_department_id);-- 带条件的MERGE
MERGE INTO products p
USING (SELECT product_id, new_price, supplier_idFROM product_price_updatesWHERE effective_date = TRUNC(SYSDATE)
) ppu
ON (p.product_id = ppu.product_id)
WHEN MATCHED THENUPDATE SET unit_price = ppu.new_price,modified_date = SYSDATEWHERE p.supplier_id = ppu.supplier_id  -- 额外条件
WHEN NOT MATCHED THENINSERT (product_id, unit_price, supplier_id, created_date)VALUES (ppu.product_id, ppu.new_price, ppu.supplier_id, SYSDATE)WHERE ppu.new_price > 0;  -- 插入条件

5.2 复杂MERGE应用

-- 数据仓库ETL场景
MERGE INTO fact_sales fs
USING (SELECT s.sale_id,s.product_id,s.customer_id,s.sale_date,s.quantity,s.unit_price,s.total_amount,p.category_id,c.region_id,EXTRACT(YEAR FROM s.sale_date) as sale_year,EXTRACT(MONTH FROM s.sale_date) as sale_monthFROM staging_sales sJOIN products p ON s.product_id = p.product_idJOIN customers c ON s.customer_id = c.customer_idWHERE s.processed_flag = 'N'
) stage
ON (fs.sale_id = stage.sale_id)
WHEN MATCHED THENUPDATE SET quantity = stage.quantity,unit_price = stage.unit_price,total_amount = stage.total_amount,last_updated = SYSDATEWHERE fs.total_amount != stage.total_amount  -- 只更新变化的记录
WHEN NOT MATCHED THENINSERT (sale_id, product_id, customer_id, sale_date,quantity, unit_price, total_amount,category_id, region_id, sale_year, sale_month,created_date) VALUES (stage.sale_id, stage.product_id, stage.customer_id, stage.sale_date,stage.quantity, stage.unit_price, stage.total_amount,stage.category_id, stage.region_id, stage.sale_year, stage.sale_month,SYSDATE);-- 库存管理MERGE
MERGE INTO inventory i
USING (SELECT product_id,SUM(CASE WHEN transaction_type = 'IN' THEN quantity ELSE -quantity END) as net_changeFROM inventory_transactionsWHERE transaction_date = TRUNC(SYSDATE)AND processed_flag = 'N'GROUP BY product_id
) it
ON (i.product_id = it.product_id)
WHEN MATCHED THENUPDATE SET quantity_on_hand = quantity_on_hand + it.net_change,last_updated = SYSDATEWHERE it.net_change != 0
WHEN NOT MATCHED THENINSERT (product_id, quantity_on_hand, last_updated)VALUES (it.product_id, it.net_change, SYSDATE)WHERE it.net_change > 0;-- 客户360度视图更新
MERGE INTO customer_360 c360
USING (WITH customer_stats AS (SELECT customer_id,COUNT(*) as total_orders,SUM(total_amount) as total_spent,AVG(total_amount) as avg_order_value,MAX(order_date) as last_order_date,MIN(order_date) as first_order_dateFROM ordersWHERE order_date >= ADD_MONTHS(SYSDATE, -12)GROUP BY customer_id),customer_segments AS (SELECT customer_id,CASE WHEN total_spent > 10000 THEN 'VIP'WHEN total_spent > 5000 THEN 'PREMIUM'WHEN total_spent > 1000 THEN 'REGULAR'ELSE 'BASIC'END as segment,CASE WHEN last_order_date > SYSDATE - 30 THEN 'ACTIVE'WHEN last_order_date > SYSDATE - 90 THEN 'INACTIVE'ELSE 'DORMANT'END as statusFROM customer_stats)SELECT cs.customer_id,cs.total_orders,cs.total_spent,cs.avg_order_value,cs.last_order_date,cs.first_order_date,seg.segment,seg.statusFROM customer_stats csJOIN customer_segments seg ON cs.customer_id = seg.customer_id
) stats
ON (c360.customer_id = stats.customer_id)
WHEN MATCHED THENUPDATE SET total_orders = stats.total_orders,total_spent = stats.total_spent,avg_order_value = stats.avg_order_value,last_order_date = stats.last_order_date,customer_segment = stats.segment,customer_status = stats.status,last_updated = SYSDATE
WHEN NOT MATCHED THENINSERT (customer_id, total_orders, total_spent, avg_order_value,last_order_date, first_order_date, customer_segment, customer_status,created_date, last_updated) VALUES (stats.customer_id, stats.total_orders, stats.total_spent, stats.avg_order_value,stats.last_order_date, stats.first_order_date, stats.segment, stats.status,SYSDATE, SYSDATE);

6. 事务控制

6.1 事务基础

事务就像是一套组合拳，要么全部成功，要么全部失败：

-- 基本事务控制
BEGININSERT INTO orders (order_id, customer_id, order_date, total_amount)VALUES (1001, 123, SYSDATE, 1500);INSERT INTO order_details (order_id, product_id, quantity, unit_price)VALUES (1001, 456, 2, 750);UPDATE inventory SET quantity_on_hand = quantity_on_hand - 2WHERE product_id = 456;COMMIT;  -- 提交所有更改
EXCEPTIONWHEN OTHERS THENROLLBACK;  -- 出错时回滚RAISE;
END;
/-- 使用保存点
DECLAREv_error_count NUMBER := 0;
BEGINSAVEPOINT start_processing;-- 第一批操作INSERT INTO batch_log (batch_id, status) VALUES (1, 'STARTED');SAVEPOINT batch1_complete;-- 第二批操作BEGINUPDATE products SET unit_price = unit_price * 1.1;INSERT INTO price_history (product_id, old_price, new_price, change_date)SELECT product_id, unit_price / 1.1, unit_price, SYSDATE FROM products;SAVEPOINT batch2_complete;EXCEPTIONWHEN OTHERS THENROLLBACK TO batch1_complete;  -- 只回滚第二批操作v_error_count := v_error_count + 1;END;-- 第三批操作BEGINDELETE FROM temp_calculations WHERE created_date < SYSDATE - 1;COMMIT;EXCEPTIONWHEN OTHERS THENROLLBACK TO batch2_complete;v_error_count := v_error_count + 1;END;IF v_error_count > 0 THENDBMS_OUTPUT.PUT_LINE('Completed with ' || v_error_count || ' errors');END IF;
END;
/

6.2 复杂事务处理

-- 银行转账事务示例
CREATE OR REPLACE PROCEDURE transfer_funds(p_from_account IN NUMBER,p_to_account IN NUMBER,p_amount IN NUMBER
)
ISv_from_balance NUMBER;v_to_balance NUMBER;insufficient_funds EXCEPTION;account_not_found EXCEPTION;
BEGINSAVEPOINT before_transfer;-- 锁定源账户并检查余额SELECT balance INTO v_from_balanceFROM accountsWHERE account_id = p_from_accountFOR UPDATE;IF v_from_balance < p_amount THENRAISE insufficient_funds;END IF;-- 锁定目标账户SELECT balance INTO v_to_balanceFROM accountsWHERE account_id = p_to_accountFOR UPDATE;-- 执行转账UPDATE accounts SET balance = balance - p_amount,last_transaction_date = SYSDATEWHERE account_id = p_from_account;UPDATE accounts SET balance = balance + p_amount,last_transaction_date = SYSDATEWHERE account_id = p_to_account;-- 记录交易历史INSERT INTO transactions (transaction_id, account_id, transaction_type, amount, balance_after)VALUES (trans_seq.NEXTVAL, p_from_account, 'DEBIT', -p_amount, v_from_balance - p_amount);INSERT INTO transactions (transaction_id, account_id, transaction_type, amount, balance_after)VALUES (trans_seq.NEXTVAL, p_to_account, 'CREDIT', p_amount, v_to_balance + p_amount);COMMIT;DBMS_OUTPUT.PUT_LINE('Transfer completed successfully');EXCEPTIONWHEN insufficient_funds THENROLLBACK TO before_transfer;RAISE_APPLICATION_ERROR(-20001, 'Insufficient funds');WHEN NO_DATA_FOUND THENROLLBACK TO before_transfer;RAISE_APPLICATION_ERROR(-20002, 'Account not found');WHEN OTHERS THENROLLBACK TO before_transfer;RAISE_APPLICATION_ERROR(-20003, 'Transfer failed: ' || SQLERRM);
END;
/-- 批量处理事务
CREATE OR REPLACE PROCEDURE process_daily_orders
ISCURSOR order_cursor ISSELECT order_id, customer_id, total_amountFROM pending_ordersWHERE order_date = TRUNC(SYSDATE)FOR UPDATE SKIP LOCKED;  -- 跳过被锁定的行v_processed_count NUMBER := 0;v_error_count NUMBER := 0;v_batch_size NUMBER := 100;BEGINFOR order_rec IN order_cursor LOOPBEGINSAVEPOINT process_order;-- 处理订单逻辑UPDATE inventory SET quantity_on_hand = quantity_on_hand - (SELECT SUM(quantity) FROM order_details WHERE order_id = order_rec.order_id)WHERE product_id IN (SELECT product_id FROM order_details WHERE order_id = order_rec.order_id);-- 更新订单状态UPDATE pending_orders SET status = 'PROCESSED',processed_date = SYSDATEWHERE order_id = order_rec.order_id;v_processed_count := v_processed_count + 1;-- 批量提交IF MOD(v_processed_count, v_batch_size) = 0 THENCOMMIT;DBMS_OUTPUT.PUT_LINE('Processed ' || v_processed_count || ' orders');END IF;EXCEPTIONWHEN OTHERS THENROLLBACK TO process_order;v_error_count := v_error_count + 1;-- 记录错误INSERT INTO error_log (error_date, error_message, order_id)VALUES (SYSDATE, SQLERRM, order_rec.order_id);END;END LOOP;COMMIT;  -- 提交剩余的更改DBMS_OUTPUT.PUT_LINE('Processing complete: ' || v_processed_count || ' processed, ' || v_error_count || ' errors');
END;
/

7. 性能优化技巧

7.1 批量操作优化

-- 高效的批量插入
DECLARETYPE number_array IS TABLE OF NUMBER;TYPE varchar_array IS TABLE OF VARCHAR2(100);TYPE date_array IS TABLE OF DATE;l_emp_ids number_array;l_names varchar_array;l_emails varchar_array;l_hire_dates date_array;v_batch_size NUMBER := 10000;
BEGIN-- 准备数据SELECT employee_id, first_name || ' ' || last_name, email, hire_dateBULK COLLECT INTO l_emp_ids, l_names, l_emails, l_hire_datesFROM external_employeesWHERE import_flag = 'Y';-- 批量插入FORALL i IN 1..l_emp_ids.COUNT SAVE EXCEPTIONSINSERT INTO employees (employee_id, full_name, email, hire_date)VALUES (l_emp_ids(i), l_names(i), l_emails(i), l_hire_dates(i));COMMIT;DBMS_OUTPUT.PUT_LINE('Inserted ' || l_emp_ids.COUNT || ' employees');EXCEPTIONWHEN OTHERS THENIF SQLCODE = -24381 THEN  -- FORALL with SAVE EXCEPTIONSFOR i IN 1..SQL%BULK_EXCEPTIONS.COUNT LOOPDBMS_OUTPUT.PUT_LINE('Error ' || i || ': ' || SQL%BULK_EXCEPTIONS(i).ERROR_CODE || ' at index ' ||SQL%BULK_EXCEPTIONS(i).ERROR_INDEX);END LOOP;END IF;RAISE;
END;
/-- 优化的大表更新
CREATE OR REPLACE PROCEDURE optimize_large_table_update
ISCURSOR update_cursor ISSELECT rowid, employee_id, salaryFROM employeesWHERE last_review_date < ADD_MONTHS(SYSDATE, -12)AND status = 'ACTIVE';TYPE rowid_array IS TABLE OF ROWID;TYPE number_array IS TABLE OF NUMBER;l_rowids rowid_array;l_new_salaries number_array;v_batch_size NUMBER := 5000;v_total_updated NUMBER := 0;
BEGINOPEN update_cursor;LOOPFETCH update_cursor BULK COLLECT INTO l_rowids, l_new_salariesLIMIT v_batch_size;EXIT WHEN l_rowids.COUNT = 0;-- 计算新薪资FOR i IN 1..l_rowids.COUNT LOOPl_new_salaries(i) := l_new_salaries(i) * 1.05;END LOOP;-- 批量更新FORALL i IN 1..l_rowids.COUNTUPDATE employeesSET salary = l_new_salaries(i),last_review_date = SYSDATEWHERE rowid = l_rowids(i);v_total_updated := v_total_updated + l_rowids.COUNT;COMMIT;DBMS_OUTPUT.PUT_LINE('Updated ' || l_rowids.COUNT || ' rows');END LOOP;CLOSE update_cursor;DBMS_OUTPUT.PUT_LINE('Total updated: ' || v_total_updated || ' rows');
END;
/

7.2 索引和查询优化

-- 使用提示优化DML
-- 强制使用特定索引
UPDATE /*+ INDEX(employees, idx_emp_dept_id) */ employees
SET salary = salary * 1.1
WHERE department_id = 20;-- 并行DML
ALTER SESSION ENABLE PARALLEL DML;
INSERT /*+ PARALLEL(sales_archive, 4) */ INTO sales_archive
SELECT * FROM sales_data WHERE sale_date < ADD_MONTHS(SYSDATE, -36);-- 使用APPEND提示减少日志
INSERT /*+ APPEND */ INTO employees_backup
SELECT * FROM employees WHERE status = 'INACTIVE';-- 优化MERGE性能
MERGE /*+ USE_HASH(target source) */ INTO customer_summary target
USING (SELECT /*+ PARALLEL(orders, 2) */customer_id,COUNT(*) as order_count,SUM(total_amount) as total_spentFROM ordersWHERE order_date >= ADD_MONTHS(SYSDATE, -12)GROUP BY customer_id
) source
ON (target.customer_id = source.customer_id)
WHEN MATCHED THENUPDATE SET order_count = source.order_count,total_spent = source.total_spent,last_updated = SYSDATE
WHEN NOT MATCHED THENINSERT (customer_id, order_count, total_spent, last_updated)VALUES (source.customer_id, source.order_count, source.total_spent, SYSDATE);-- 分区智能操作
-- 只操作相关分区
INSERT INTO sales_data PARTITION (sales_2024_q1)
SELECT * FROM staging_sales 
WHERE sale_date BETWEEN DATE '2024-01-01' AND DATE '2024-03-31';-- 分区交换（快速数据移动）
ALTER TABLE sales_data EXCHANGE PARTITION sales_2023_q1 
WITH TABLE sales_2023_q1_archive;

结语
感谢您的阅读！期待您的一键三连！欢迎指正！