MySQL - INTERSECT 相交运算符
在数学集合论中,两个集合的交集是指仅包含两个集合共有元素的集合。换句话说,两个集合的交集是两个集合中都存在的元素的集合。
如果我们使用 INTERSECT 运算符对两个集合执行交集运算,则会显示两个表中相同的行。此运算符会从最终结果集中删除重复的行。
MySQL INTERSECT 运算符
在 MySQL 中,INTERSECT 运算符用于返回两个 SELECT(表)语句的结果集之间相同/相同的记录。
但是,只有当两个 SELECT 语句的列数相同且数据类型和名称相同时,INTERSECT 运算符才有效。
语法
以下是 MySQL 中 INTERSECT 运算符的语法 -
SELECT column1, column2,..., columnN FROM table1, table2,..., tableN INTERSECT SELECT column1, column2,..., columnN FROM table1, table2,..., tableN
示例
首先,我们使用以下查询创建一个名为 STUDENTS 的表 -
CREATE TABLE STUDENTS( ID INT NOT NULL, NAME VARCHAR(20) NOT NULL, HOBBY VARCHAR(20) NOT NULL, AGE INT NOT NULL, PRIMARY KEY(ID) );
在这里,我们使用 INSERT 语句向表中插入一些值。
INSERT INTO STUDENTS VALUES (1, 'Vijay', 'Cricket', 18), (2, 'Varun', 'Football', 26), (3, 'Surya', 'Cricket', 19), (4, 'Karthik', 'Cricket', 25), (5, 'Sunny', 'Football', 26), (6, 'Dev', 'Cricket', 23);
表的创建如下 -
ID | NAME | HOBBY | AGE |
---|---|---|---|
1 | Vijay | Cricket | 18 |
2 | Varun | Football | 26 |
3 | Surya | Cricket | 19 |
4 | Karthik | Cricket | 25 |
5 | Sunny | Football | 26 |
6 | Dev | Cricket | 23 |
现在,让我们使用以下查询创建另一个名为ASSOCIATES的表 -
CREATE TABLE ASSOCIATES( ID INT NOT NULL, NAME VARCHAR(20) NOT NULL, SUBJECT VARCHAR(20) NOT NULL, AGE INT NOT NULL, HOBBY VARCHAR(20) NOT NULL, PRIMARY KEY(ID) );
在这里,我们使用INSERT语句将一些值插入表中 -
INSERT INTO ASSOCIATES VALUES (1, 'Naina', 'Maths', 24, 'Cricket'), (2, 'Varun', 'Physics', 26, 'Football'), (3, 'Dev', 'Maths', 23, 'Cricket'), (4, 'Priya', 'Physics', 25, 'Cricket'), (5, 'Aditya', 'Chemistry', 21, 'Cricket'), (6, 'Kalyan', 'Maths', 30, 'Football');
表的创建如下 -
ID | NAME | SUBJECT | AGE | HOBBY |
---|---|---|---|---|
1 | Naina | Maths | 24 | Cricket |
2 | Varun | Physics | 26 | Football |
3 | Dev | Maths | 23 | Cricket |
4 | Priya | Physics | 25 | Cricket |
5 | Aditya | Chemistry | 21 | Cricket |
6 | Kalyan | Maths | 30 | Football |
现在,我们使用以下查询从两个表中返回公共记录 -
SELECT NAME, AGE, HOBBY FROM STUDENTS INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES;
输出
输出结果如下 -
NAME | AGE | HOBBY |
---|---|---|
Varun | 26 | Football |
Dev | 23 | Cricket |
INTERSECT 与 BETWEEN 运算符
MySQL INTERSECT 运算符可以与 BETWEEN 运算符一起使用,以查找指定范围内的行。
示例
在以下查询中,我们将检索两个表中相同的记录。此外,我们还将检索年龄在 25 至 30 岁之间的记录 -
SELECT NAME, AGE, HOBBY FROM STUDENTS WHERE AGE BETWEEN 25 AND 30 INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES WHERE AGE BETWEEN 20 AND 30;
输出
执行给定程序后,输出如下:
NAME | AGE | HOBBY |
---|---|---|
Varun | 26 | Football |
使用 IN 运算符进行 INTERSECT 查询
在 MySQL 中,我们可以使用 INTERSECT 运算符和 IN 运算符来查找包含指定值的公共行。IN 运算符用于根据指定值的列表筛选结果集。
示例
在下面的查询中,我们尝试从两个表中返回公共记录。此外,我们还使用 IN 运算符来检索爱好为"Cricket"的记录。
SELECT NAME, AGE, HOBBY FROM STUDENTS WHERE HOBBY IN('Cricket') INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES WHERE HOBBY IN('Cricket');
输出
上述程序的输出如下所示 -
NAME | AGE | HOBBY |
---|---|---|
Dev | 23 | Cricket |
使用 LIKE 运算符进行 INTERSECT 查询
LIKE 运算符用于对字符串值进行模式匹配。
在 MySQL 中,我们可以将 LIKE 运算符与 INTERSECT 运算符结合使用,以查找符合指定模式的公共行。
示例
在下面的查询中,我们将通配符"%"与 LIKE 运算符结合使用,从两个表的公共名称中获取带有"v"的名称。
SELECT NAME, AGE, HOBBY FROM STUDENTS WHERE NAME LIKE 'v%' INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES WHERE NAME LIKE 'v%';
输出
编译并运行程序,结果如下:
NAME | AGE | HOBBY |
---|---|---|
Varun | 26 | Football |
使用客户端程序执行相交运算符
除了在 MySQL 服务器中执行相交运算符外,我们还可以使用客户端程序对表执行相交运算符。
语法
以下是不同编程语言中 MySQL 表中相交运算符的语法 -
要通过 PHP 程序在 MySQL 表中执行 Intersect 运算符,我们需要使用 mysqli 连接器的 query() 函数执行 INTERSECT 语句。
$sql = "SELECT column1, column2,..., columnN FROM table1, table2,..., tableN INTERSECT SELECT column1, column2,..., columnN FROM table1, table2,..., tableN"; $mysqli->query($sql);
要通过 JavaScript 程序在 MySQL 表中执行 Intersect 运算符,我们需要使用 mysql2 连接器的 query() 函数执行 INTERSECT 语句。
sql = "SELECT column1, column2,..., columnN FROM table1, table2,..., tableN INTERSECT SELECT column1, column2,..., columnN FROM table1, table2,..., tableN"; con.query(sql);
要通过 Java 程序在 MySQL 表中执行 Intersect 运算符,我们需要使用 JDBC type 4 驱动程序的 executeQuery() 函数执行 INTERSECT 语句。
String sql = "SELECT column1, column2,..., columnN FROM table1, table2,..., tableN INTERSECT SELECT column1, column2,..., columnN FROM table1, table2,..., tableN"; statement.executeQuery(sql);
要通过 Python 程序在 MySQL 表中执行 Intersect 运算符,我们需要使用 MySQL Connector/Python 提供的 execute() 函数执行 INTERSECT 语句。
intersect_query = SELECT column1, column2,..., column FROM table1, table2,..., tableN INTERSECT SELECT column1, column2,..., column FROM table1, table2,..., tableN cursorObj.execute(intersect_query);
示例
以下是此操作在各种编程语言中的实现 -
$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.
'); $sql = "SELECT NAME, AGE, HOBBY FROM STUDENTS INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES;"; $result = $mysqli->query($sql); if ($result->num_rows > 0) { printf("Table records: "); while($row = $result->fetch_assoc()) { printf("NAME %s, AGE %d, HOBBY %s", $row["NAME"], $row["AGE"], $row["HOBBY"],); printf(" "); } } else { printf('No record found.
'); } mysqli_free_result($result); $mysqli->close();
输出
获得的输出如下 -
Table records: NAME Varun, AGE 26, HOBBY Football NAME Dev, AGE 23, HOBBY Cricket
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("--------------------------"); //创建数据库 sql = "create database TUTORIALS" con.query(sql); //选择数据库 sql = "USE TUTORIALS" con.query(sql); //Creating STUDENTS table sql = "CREATE TABLE STUDENTS(ID INT NOT NULL,NAME VARCHAR(20) NOT NULL,HOBBY VARCHAR(20) NOT NULL,AGE INT NOT NULL,PRIMARY KEY(ID));" con.query(sql); //插入记录 sql = "INSERT INTO STUDENTS(ID, NAME, HOBBY, AGE) VALUES(1, 'Vijay', 'Cricket',18),(2, 'Varun','Football', 26),(3, 'Surya', 'Cricket',19),(4, 'Karthik','Cricket', 25),(5, 'Sunny','Football', 26),(6, 'Dev', 'Cricket',23);" con.query(sql); //Creating ASSOCIATES table sql = "CREATE TABLE ASSOCIATES(ID INT NOT NULL,NAME VARCHAR(20) NOT NULL,SUBJECT VARCHAR(20) NOT NULL,AGE INT NOT NULL,HOBBY VARCHAR(20) NOT NULL,PRIMARY KEY(ID));" con.query(sql); //插入记录 sql = "INSERT INTO ASSOCIATES(ID, NAME, SUBJECT, AGE, HOBBY) VALUES(1, 'Naina','Maths', 24, 'Cricket'),(2, 'Varun','Physics', 26, 'Football'),(3, 'Dev','Maths', 23, 'Cricket'),(4, 'Priya','Physics', 25, 'Cricket'),(5,'Aditya', 'Chemistry', 21, 'Cricket'),(6,'Kalyan', 'Maths', 30, 'Football');" con.query(sql); //使用 INTERSECT 运算符 sql = "SELECT NAME, AGE, HOBBY FROM STUDENTS INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES;" con.query(sql, function(err, result){ if (err) throw err console.log(result) }); });
输出
生成的输出如下 -
Connected! -------------------------- [ { NAME: 'Varun', AGE: 26, HOBBY: 'Football' }, { NAME: 'Dev', AGE: 23, HOBBY: 'Cricket' } ]
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class IntersectOperator { 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 NAME, AGE, HOBBY FROM STUDENTS INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES"; rs = st.executeQuery(sql); System.out.println("Table records: "); while(rs.next()) { String name = rs.getString("NAME"); String age = rs.getString("AGE"); String hobby = rs.getString("HOBBY"); System.out.println("Name: " + name + ", Age: " + age + ", Hobby: " + hobby); } }catch(Exception e) { e.printStackTrace(); } } }
输出
获得的输出如下所示 -
Table records: Name: Varun, Age: 26, Hobby: Football Name: Dev, Age: 23, Hobby: Cricket
import mysql.connector #建立连接 connection = mysql.connector.connect( host='localhost', user='root', password='password', database='tut' ) cursorObj = connection.cursor() intersect_query = f""" SELECT NAME, AGE, HOBBY FROM STUDENTS INTERSECT SELECT NAME, AGE, HOBBY FROM ASSOCIATES; """ cursorObj.execute(intersect_query) # 获取所有符合条件的行 filtered_rows = cursorObj.fetchall() for row in filtered_rows: print(row) cursorObj.close() connection.close()
输出
以下是上述代码的输出 -
('Varun', 26, 'Football') ('Dev', 23, 'Cricket')