INSERT~SELECT (从一个表select内容，insert到另一个表)

本篇是关于
SELECT 表B table B的内容，INSERT到 表A table A 中的SQL 的。

SQL

• 定义相同的两个table，全件insert

INSERT INTO table_A
SELECT * 
FROM table_B;

• 指定字段insert

INSERT INTO table_A(
     字段1
    ,字段2
)
SELECT 字段1
      ,字段2
FROM table_B;

• 指定条件，将select的结果insert

INSERT INTO table_A(
     字段1
    ,字段2
)
SELECT 字段1
      ,字段2
FROM table_B
WHERE 条件;

例

数据准备

CREATE TABLE test_db.insert_table (
  `id` INT AUTO_INCREMENT NOT NULL,
  `name` VARCHAR(45) NOT NULL,
  `age` INT,
  PRIMARY KEY (`id`));
  
CREATE TABLE test_db.insert_table2 (
  `id` INT AUTO_INCREMENT NOT NULL,
  `name` VARCHAR(45) NOT NULL,
  `age` INT,
  PRIMARY KEY (`id`));
  
INSERT INTO test_db.insert_table2 (name,age)
VALUES ('Joey',27), 
('Jack',34), 
('John',52), 
('Ryan',25), 
('May',22);

两个表的当前内容：

mysql> SELECT * FROM test_db.insert_table;
Empty set (0.01 sec)

mysql> SELECT * FROM test_db.insert_table2;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | Joey |   27 |
|  2 | Jack |   34 |
|  3 | John |   52 |
|  4 | Ryan |   25 |
|  5 | May  |   22 |
+----+------+------+
5 rows in set (0.00 sec)

• 执行SQL 例1，

INSERT INTO insert_table
SELECT *
FROM insert_table2; 

执行结果

mysql> SELECT * FROM test_db.insert_table;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | Joey |   27 |
|  2 | Jack |   34 |
|  3 | John |   52 |
|  4 | Ryan |   25 |
|  5 | May  |   22 |
+----+------+------+
5 rows in set (0.00 sec)

• 执行 SQL 例2，

INSERT INTO insert_table (
id,
name
)
SELECT insert_table2.id, 
insert_table2.name
FROM insert_table2;

执行结果

mysql> SELECT * FROM test_db.insert_table;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | Joey | NULL |
|  2 | Jack | NULL |
|  3 | John | NULL |
|  4 | Ryan | NULL |
|  5 | May  | NULL |
+----+------+------+
5 rows in set (0.00 sec)

• 执行SQL 例3，

INSERT INTO insert_table (
name, 
age)
SELECT insert_table2.name, 
insert_table2.age
FROM insert_table2
WHERE insert_table2.age >= 30; 

执行结果，

mysql> SELECT * FROM test_db.insert_table;
+----+------+------+
| id | name | age  |
+----+------+------+
|  1 | Jack |   34 |
|  2 | John |   52 |
+----+------+------+
2 rows in set (0.00 sec)

执行例子，每次insert前可以清空一下表insert_table：
truncate table insert_table;

以上。