1、INSERT INTO SELECT结合语法详解
语句从一个表复制数据，然后把数据插入到一个已存在的表中。
其基本的书写格式为：
INSERT INTO table2 （c1,c2,c3...） SELECT c1,c2,c3... FROM table1 where ... 注意：
（1）要求目标表Table2和源表Table1必须存在，并且字段相应也必须存在
（2）注意Table2的主键约束，如果Table2有主键而且不为空，则 field1， field2…中必须包括主键
（3）注意语法，不要加values，和插入一条数据的sql混了
INSERT INTO SELECT的特殊用法：与dual表结合(dual表：存在的最小的工作表，永远只有一条记录）
（1）、与单条插入的sql语句的等价形式
//val1,val2,val3是具体的值
INSERT INTO table2 （c1,c2,c3...） select val1，val2，val3... from dual
//举例：等价于 INSERT INTO table2 （name,age,sex）values（'ian','21','male'）
INSERT INTO table2 （name,age,sex） select 'ian','21','male' from dual
（2）、insert插入sql的条件判断：若不存在则插入
INSERT INTO table2 （c1,c2,c3...） select val1，val2，val3... from dual where not exists(select * from table2 where c1 = 'val1')
2、通用update语法详解
一般简单的update语法比较通用
UPDATE table_name
SET column1=value1,
column2=value2,
...
WHERE some_column = some_value;
注：若不加where条件则是更新表中的所有数据，
故执行没有where子句的update要慎重再慎重。
实例：
UPDATE subject
SET name='英语',
type='语文'
WHERE id = 1;
3、MySQL update与select结合
第一种：
UPDATE table1 SET column1 = (SELECT column FROM table2 [WHERE condition])
WHERE table1.column2 = value;
注：若不加where条件则是更新表中的所有数据，
故执行没有where子句的update要慎重再慎重。
实例：
UPDATE tb_bookcase
SET name = (SELECT bookname FROM tb_bookinfo WHERE tb_bookinfo.type = tb_bookcase.type
AND tb_bookinfo.ord_date IN (SELECT MAX(ord_date) FROM tb_bookinfo))
WHERE tb_bookcase.subject = '学习';
第二种：
UPDATE table1 inner/left/right join table2/(select columns from table3
[inner/left/right join on condition] [where conditions]) as t3
ON condition
SET column1 = value1,column2 = value2,...
[WHERE conditions];
实例：
UPDATE $table1 a INNER JOIN $table2 b
ON a.user_id = b.user_id
SET a.balance = a.balance + b.income,b.status= 1
WHERE b.id = 5 AND b.status = 0；
例2：
UPDATE A INNER JOIN
(SELECT B.B1 as B1,B.B2 as B2,C.C1 as C1 from B LEFT JOIN C on
B.B3=C.C3) as t
ON A.A3=t.B1
set A.A1=t.B2,
A.A2=t.C1;
UPDATE tb_bookcase INNER JOIN
(SELECT tb_bookinfo.rid as rid,tb_bookinfo.bookname,department.name LEFT JOIN department on
tb_bookinfo.depid=department.id) as t
ON tb_bookcase.id=t.rid
set tb_bookcase.bookname=t.bookname,
tb_bookcase.departname=t.name ;
4、Oracle update与select结合
语法：
UPDATE table1 alias
SET (column_name,column_name ) = (
SELECT column_name, column_name FROM table2 WHERE table2.column_name = alias.column_name)
[WHERE column_name = VALUE]
注：若不加where条件则是更新表中的所有数据，
故执行没有where子句的update要慎重再慎重。
UPDATE t_order t1
SET (ordername,orderprice) = (SELECT detailname,totalprice FROM t_detail WHERE t_detail.detailclasses = t1.classes)
WHERE t1.orderid = 1
例2：
UPDATE A SET (A1, A2, A3) = (SELECT B1, B2, B3 FROM B WHERE A.ID = B.ID)
WHERE ID IN (SELECT B.ID FROM B WHERE A.ID = B.ID)
5、SQLServer update与select结合
UPDATE table1
SET column1 = t2.column1,
column1 = t2.column2,
...
FROM table1 INNER/LEFT/RIGHT JOIN table2 ON table1.column = table2.column
[WHERE conditions]
注：若不加where条件则是更新表中的所有数据，
故执行没有where子句的update要慎重再慎重。
UPDATE A
SET A1 = t2.B2 ,
A2 = t2.C1
FROM A INNER JOIN (
SELECT B.B1,B.B2,C.C1
FROM B left join C on B.B3 = C.C3) t2
ON A.A3 = t2.B1
WHERE A.A4 = 1;
UPDATE t_abnormal_fee
SET order_code = t2.order_code ,
return_fee = t2.express_fee
FROM t_abnormal_fee INNER JOIN (
SELECT t_order.id,t_order.order_code,t_detail.express_fee
FROM t_order left join t_detail on t_order.name = t_detail.name) t2
ON t_abnormal_fee.id = t2.id
WHERE t_abnormal_fee.id = 1;