MySQL - INSERT INTO Select 语句
MySQL 插入到 Select 语句
在 MySQL 中,INSERT INTO...SELECT 语句用于添加/插入一行或多行从现有表插入到目标表。
此语句由两个不同的语句组成:INSERT INTO 和 SELECT。
- MySQL INSERT INTO 语句是数据库管理中常用的命令,它只需要表名和要插入到表中的值。但是,务必确保插入的数据与表列的结构和数据类型匹配。
- SELECT 语句用于从现有数据库表中获取数据。
当上述语句一起使用时,SELECT 语句首先从现有表中获取数据,然后 INSERT INTO 语句将检索到的数据插入到另一个表中(如果它们具有相同的表结构)。
语法
以下是使用 insert into select 语句的语法 -
INSERT INTO table2 (column1, column2, column3, ...) SELECT column1, column2, column3, ... FROM table1 WHERE condition;
在执行以下查询之前,我们需要考虑以下几个要点 -
- 在我们要插入数据的数据库中,必须已经存在一个表。
- 源表和目标表的结构都必须匹配。
示例
首先,我们使用以下查询创建一个名为 CUSTOMERS 的表 -
CREATE TABLE CUSTOMERS ( ID INT NOT NULL, NAME VARCHAR(20) NOT NULL, AGE INT NOT NULL, ADDRESS CHAR (25), SALARY DECIMAL (18, 2), PRIMARY KEY (ID) );
以下查询将 7 条记录插入到上面创建的表中 -
INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY) VALUES (1, 'Ramesh', 32, 'Ahmedabad', 2000.00 ), (2, 'Khilan', 25, 'Delhi', 1500.00 ), (3, 'Kaushik', 23, 'Kota', 2000.00 ), (4, 'Chaitali', 25, 'Mumbai', 6500.00 ), (5, 'Hardik', 27, 'Bhopal', 8500.00 ), (6, 'Komal', 22, 'Hyderabad', 4500.00 ), (7, 'Muffy', 24, 'Indore', 10000.00 );
执行以下查询以检索 CUSTOMERS 表中的所有记录 -
Select * From CUSTOMERS;
以下是 CUSTOMERS 表 -
ID | NAME | AGE | ADDRESS | SALARY |
---|---|---|---|---|
1 | Ramesh | 32 | Ahmedabad | 2000.00 |
2 | Khilan | 25 | Delhi | 1500.00 |
3 | Kaushik | 23 | Kota | 2000.00 |
4 | Chaitali | 25 | Mumbai | 6500.00 |
5 | Hardik | 27 | Bhopal | 8500.00 |
6 | Komal | 22 | Hyderabad | 4500.00 |
7 | Muffy | 24 | Indore | 10000.00 |
将所需数据从一个表插入到另一个表
我们可能会遇到一些只想向另一个表添加少量记录的情况。这可以通过使用 WHERE 子句来选择查询返回的所有行来实现。
示例
在此之前,让我们创建一个名为 CUSTOMERS_copy 的表,其结构与之前创建的 CUSTOMERS 表类似 -
CREATE TABLE CUSTOMERS_copy ( ID INT AUTO_INCREMENT, NAME VARCHAR(20) NOT NULL, AGE INT NOT NULL, ADDRESS CHAR (25), SALARY DECIMAL (18, 2), PRIMARY KEY (ID) );
在以下查询中,我们尝试从 CUSTOMERS 表中获取记录并将其插入到 CUSTOMERS_copy 表中。
INSERT INTO CUSTOMERS_copy (ID, NAME, AGE, ADDRESS, SALARY) SELECT ID, NAME, AGE, ADDRESS, SALARY FROM CUSTOMERS WHERE AGE >= 25;
输出
上述程序的输出如下所示 -
Query OK, 4 rows affected (0.01 sec) Records: 4 Duplicates: 0 Warnings: 0
验证
要确认"CUSTOMERS"表中年龄为 25 岁及以上的记录是否已插入目标表"CUSTOMERS_copy",请执行以下查询 -
SELECT * FROM CUSTOMERS_copy;
以下是年龄为 25 岁及以上的记录 -
ID | NAME | AGE | ADDRESS | SALARY |
---|---|---|---|---|
1 | Ramesh | 32 | Ahmedabad | 2000.00 |
2 | Khilan | 25 | Delhi | 1500.00 |
4 | Chaitali | 25 | Mumbai | 6500.00 |
5 | Hardik | 27 | Bhopal | 8500.00 |
使用 LIMIT 插入行
使用 MySQL LIMIT 子句,我们可以指定查询中应添加到目标表的行数。
示例
在继续操作之前,我们首先使用以下查询截断 CUSTOMERS_copy 表中的所有行 -
TRUNCATE TABLE CUSTOMERS_copy;
现在,我们将使用 LIMIT 子句从 CUSTOMERS 表中插入按年龄排序的前 3 条记录 -
INSERT INTO CUSTOMERS_copy (ID, NAME, AGE, ADDRESS, SALARY) SELECT ID, NAME, AGE, ADDRESS, SALARY FROM CUSTOMERS ORDER BY AGE LIMIT 3;
输出
上述程序的输出如下所示 -
Query OK, 3 rows affected (0.01 sec) Records: 3 Duplicates: 0 Warnings: 0
验证
执行以下查询,验证记录是否反映在 CUSTOMERS_copy 表中 -
SELECT * FROM CUSTOMERS_copy;
以下是记录 -
ID | NAME | AGE | ADDRESS | SALARY |
---|---|---|---|---|
3 | Kaushik | 23 | Kota | 2000.00 |
6 | Komal | 22 | Hyderabad | 4500.00 |
7 | Muffy | 24 | Indore | 10000.00 |
将一个表的所有列插入另一个表
我们也可以将一个表的所有列插入另一个表。语法如下:-
INSERT INTO table2 SELECT * FROM table1
在插入所有记录之前,首先使用以下语句截断 CUSTOMERS_copy 表中的所有行:-
TRUNCATE TABLE CUSTOMERS_copy;
在以下查询中,我们尝试将 CUSTOMERS 表中的所有列添加到 CUSTOMERS_copy 表中 -
INSERT INTO CUSTOMERS_copy SELECT * FROM CUSTOMERS;
输出
所有列均已插入,没有任何错误。
Query OK, 7 rows affected (0.01 sec) Records: 7 Duplicates: 0 Warnings: 0
验证
我们可以通过使用 SELECT 语句检索 CUSTOMERS_copy 表的内容来验证更改是否反映在表中。
SELECT * FROM CUSTOMERS_copy;
以下是 CUSTOMERS_copy 表的内容 -
ID | NAME | AGE | ADDRESS | SALARY |
---|---|---|---|---|
1 | Ramesh | 32 | Ahmedabad | 2000.00 |
2 | Khilan | 25 | Delhi | 1500.00 |
3 | Kaushik | 23 | Kota | 2000.00 |
4 | Chaitali | 25 | Mumbai | 6500.00 |
5 | Hardik | 27 | Bhopal | 8500.00 |
6 | Komal | 22 | Hyderabad | 4500.00 |
7 | Muffy | 24 | Indore | 10000.00 |
使用客户端程序执行 INSERT INTO SELECT 操作
除了使用 MySQL 查询执行 INSERT INTO ... SELECT 语句外,我们还可以使用 Node.js、PHP、Java 和 Python 等客户端程序来实现相同的结果。
语法
以下是此操作在各种编程语言中的语法 -
要通过 PHP 程序将数据从另一个 MySQL 表插入到另一个 MySQL 表中,我们需要使用 mysqli 函数 query() 执行"INSERT INTO SELECT"语句,如下所示 -
$sql = "INSERT INTO new_tutorials_tbl SELECT * FROM tutorials_tbl WHERE tutorial_id = 2"; $mysqli->query($sql);
要通过 Node.js 程序将数据从另一个 MySQL 表插入到另一个 MySQL 表中,我们需要使用 mysql2 库的 query() 函数执行"INSERT INTO SELECT"语句,如下所示 -
sql = "INSERT INTO Agentdemo(ID, NAME, GENDER, AGE) SELECT ID, NAME, GENDER, AGE FROM Agent WHERE GENDER = 'Male'"; con.query(sql);
要通过 Java 程序将数据从另一个表插入到一个 MySQL 表中,我们需要使用 JDBC 函数 executeUpdate() 执行"INSERT INTO SELECT"语句,如下所示 -
String sql = "INSERT INTO Agentdemo(ID, NAME, GENDER, AGE) SELECT ID, NAME, GENDER, AGE FROM Agent WHERE GENDER = \"Male\""; st.executeUpdate(sql);
要通过 Python 程序将数据从另一个表插入到一个 MySQL 表中,我们需要使用 MySQL Connector/Python 的 execute() 函数执行"INSERT INTO SELECT"语句,如下所示 -
sql = "INSERT INTO new_tutorials_tbl (tutorial_id, tutorial_title, tutorial_author, submission_date) SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl" insert_into_select_query = sql cursorObj.execute(insert_into_select_query)
示例
以下是程序 -
$dbhost = 'localhost'; $dbuser = 'root'; $dbpass = 'password'; $dbname = 'TUTORIALS'; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); if($mysqli->connect_errno ) { printf("Connect failed: %s
", $mysqli->connect_error); exit(); } //printf('Connected successfully.
'); $q = "SELECT * FROM new_tutorials_tbl"; if($res = $mysqli->query($q)){ printf("Select query executed successfully..! "); printf("The table 'new_tutorials_tbl' records before insert into select query: "); while($r = mysqli_fetch_array($res)){ print_r ($r); } } $sql = "INSERT INTO new_tutorials_tbl SELECT * FROM tutorials_tbl WHERE tutorial_id = 2"; if($result = $mysqli->query($sql)){ printf("Insert into select query executed successfully..! "); } $q = "SELECT * FROM new_tutorials_tbl"; if($res = $mysqli->query($q)){ printf("Select query executed successfully..! "); printf("The table 'new_tutorials_tbl' records after insert into select query: "); while($r = mysqli_fetch_array($res)){ print_r ($r); } } if($mysqli->error){ printf("Failed..!" , $mysqli->error); } $mysqli->close();
输出
获得的输出如下 -
Select query executed successfully..! The table 'new_tutorials_tbl' records before insert into select query: Array ( [0] => 1 [tutorial_id] => 1 [1] => Java Tutorial [tutorial_title] => Java Tutorial [2] => new_author [tutorial_author] => new_author [3] => [submission_date] => ) Insert into select query executed successfully..! Select query executed successfully..! The table 'new_tutorials_tbl' records after insert into select query: Array ( [0] => 1 [tutorial_id] => 1 [1] => Java Tutorial [tutorial_title] => Java Tutorial [2] => new_author [tutorial_author] => new_author [3] => [submission_date] => ) Array ( [0] => 2 [tutorial_id] => 2 [1] => PHP Tut [tutorial_title] => PHP Tut [2] => unknown2 [tutorial_author] => unknown2 [3] => 2023-08-12 [submission_date] => 2023-08-12 )
var mysql = require('mysql2'); var con = mysql.createConnection({ host: "localhost", user: "root", password: "Nr5a0204@123" }); //连接到 MySQL con.connect(function (err) { if (err) throw err; console.log("Connected!"); console.log("----------------------------------------"); //选择数据库 sql = "USE TUTORIALS" con.query(sql); sql = "CREATE TABLE Agent (ID int NOT NULL,NAME varchar(20) NOT NULL,GENDER varchar(20) NOT NULL,AGE int NOT NULL,PRIMARY KEY(ID));" con.query(sql); sql = "INSERT INTO Agent VALUES (1,'Msd', 'Male', 21), (2,'Virat', 'Male', 23), (3,'Perry', 'Female', 24), (4,'Smiti', 'Female', 18), (5,'Rose', 'Female', 23);" con.query(sql); sql = "SELECT * FROM Agent;" con.query(sql, function (err, result) { if (err) throw err; console.log(result); console.log("-------------------------------------------------------"); }); sql = "CREATE TABLE Agentdemo(ID int NOT NULL,NAME varchar(50) NOT NULL,GENDER varchar(20) NOT NULL,AGE int NOT NULL,PRIMARY KEY(ID));" con.query(sql); //将所需数据从一个表插入到另一个表 sql = "INSERT INTO Agentdemo(ID, NAME, GENDER, AGE) SELECT ID, NAME, GENDER, AGE FROM Agent WHERE GENDER = 'Male'"; con.query(sql); sql = "SELECT * FROM Agentdemo;" con.query(sql, function (err, result) { if (err) throw err; console.log(result); }); });
输出
生成的输出如下 -
Connected! ---------------------------------------- [ { ID: 1, NAME: 'Msd', GENDER: 'Male', AGE: 21 }, { ID: 2, NAME: 'Virat', GENDER: 'Male', AGE: 23 }, { ID: 3, NAME: 'Perry', GENDER: 'Female', AGE: 24 }, { ID: 4, NAME: 'Smiti', GENDER: 'Female', AGE: 18 }, { ID: 5, NAME: 'Rose', GENDER: 'Female', AGE: 23 } ] ------------------------------------------------------- [ { ID: 1, NAME: 'Msd', GENDER: 'Male', AGE: 21 }, { ID: 2, NAME: 'Virat', GENDER: 'Male', AGE: 23 } ]
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class InsertIntoSelect { public static void main(String[] args) { String url = "jdbc:mysql://localhost:3306/TUTORIALS"; String user = "root"; String password = "password"; ResultSet rs; try { Class.forName("com.mysql.cj.jdbc.Driver"); Connection con = DriverManager.getConnection(url, user, password); Statement st = con.createStatement(); //System.out.println("Database connected successfully...!"); String sql = "SELECT * FROM Agent"; rs = st.executeQuery(sql); System.out.println("Agent table records: "); while(rs.next()) { String id = rs.getString("Id"); String name = rs.getString("Name"); String gender = rs.getString("Gender"); String age = rs.getString("Age"); System.out.println("Id: " + id + ", Name: " + name + "Gender: " + gender + ", Age: " + age); } String sql1 = "SELECT * FROM Agentdemo"; rs = st.executeQuery(sql1); System.out.println("Agentdemo table before after insert into select: "); while(rs.next()) { String id = rs.getString("Id"); String name = rs.getString("Name"); String gender = rs.getString("Gender"); String age = rs.getString("Age"); System.out.println("Id: " + id + ", Name: " + name + "Gender: " + gender + ", Age: " + age); } //now let use the insert into select query String sql2 = "INSERT INTO Agentdemo(ID, NAME, GENDER, AGE) SELECT ID, NAME, GENDER, AGE FROM Agent WHERE GENDER = \"Male\""; st.executeUpdate(sql2); String sql3 = "SELECT * FROM Agentdemo"; rs = st.executeQuery(sql3); System.out.println("Agentdemo table after after insert into select: "); while(rs.next()) { String id = rs.getString("Id"); String name = rs.getString("Name"); String gender = rs.getString("Gender"); String age = rs.getString("Age"); System.out.println("Id: " + id + ", Name: " + name + "Gender: " + gender + ", Age: " + age); } }catch(Exception e) { e.printStackTrace(); } } }
输出
获得的输出如下所示 -
Agent table records: Id: 1, Name: MsdGender: Male, Age: 21 Id: 2, Name: ViratGender: Male, Age: 23 Id: 3, Name: PerryGender: Female, Age: 24 Id: 4, Name: SmitiGender: Female, Age: 18 Id: 5, Name: RoseGender: Female, Age: 23 Agentdemo table before after insert into select: Agentdemo table after after insert into select: Id: 1, Name: MsdGender: Male, Age: 21 Id: 2, Name: ViratGender: Male, Age: 23
import mysql.connector #建立连接 connection = mysql.connector.connect( host='localhost', user='root', password='password', database='tut' ) cursorObj = connection.cursor() insert_into_select_query = "INSERT INTO new_tutorials_tbl (tutorial_id, tutorial_title, tutorial_author, submission_date) SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl" cursorObj.execute(insert_into_select_query) connection.commit() print("Data inserted into new table successfully.") cursorObj.close() connection.close()
输出
以下是上述代码的输出 -
Data inserted into new table successfully.