sql insert into select 的用法

INSERT INTO SELECT语句

语句形式为：Insert into Table2(field1,field2,...) value1,value2,... from Table1

要求目标表Table2必须存在，由于目标表Table2已经存在，所以我们除了插入源表Table1的字段外，还可以插入常量

SQL>
SQL>
SQL> CREATE TABLE employee (
2 id number,
3 name varchar(100),
4 birth_date date,
5 gender varchar2(30) );

Table created.

SQL>
SQL>
SQL> INSERT INTO employee (id,name,birth_date,gender )
2 SELECT 200,'Chris',NULL,'MALE' from DUAL;

1 row created.

SQL>
SQL>
SQL> drop table employee;

Table dropped.

SELECT INTO FROM语句

语句形式为：SELECT vale1, value2 into Table2 from Table1

要求目标表Table2不存在，因为在插入时会自动创建表Table2，并将Table1中指定字段数据复制到Table2中。示例如下：

带有条件选择where

SQL>
SQL> CREATE TABLE employee (
2 id number,
3 name varchar(100),
4 birth_date date,
5 gender varchar2(30) );

Table created.

SQL>
SQL> INSERT INTO employee (id,name,birth_date,gender ) SELECT 300,'H',NULL,'MALE' from dual d
2 where not exists (SELECT 1 FROM employee x WHERE x.id = '300' );

1 row created.

SQL>
SQL> select * from employee;

ID
------
NAME
----------------------------------------------------------------------
BIRTH_DATE GENDER
---------- ------------------------------
300
H
null MALE

Insert bulk by insert ... into ... select

SQL>
SQL> CREATE TABLE project (
2 pro_id NUMBER(4),
3 pro_name VARCHAR2(40),
4 budget NUMBER(9,2),
5 CONSTRAINT project_pk PRIMARY KEY (pro_id)
6 );

Table created.

SQL>
SQL>
SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1001, 'A',12345);

1 row created.

SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1002, 'ERP',23456);

1 row created.

SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1003, 'SQL',34567);

1 row created.

SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1004, 'CRM',45678);

1 row created.

SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1005, 'VPN',56789);

1 row created.

SQL>
SQL>
SQL> SET ECHO ON
SQL> INSERT INTO PROJECT (pro_id, pro_name)
2 SELECT pro_id+8000,
3 SUBSTR(pro_name,1,31) || ' Overhead'
4 FROM project;

5 rows created.