[BAEL-8517] Multiple SQL statements as one in JDBC (#18160)

* Initial commit for BAEL-8803

* Remove service test

* Initial commit

* Review 1 updates

* Update to Live test

* Review comments

* Review comments

* AssertJ

Author: sdhiray7

persistence-modules/core-java-persistence-4/src/main/java/com/baeldung/sql/MultipleSQLExecution.java

@@ -0,0 +1,73 @@
+package com.baeldung.sql;
+
+import java.sql.CallableStatement;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+
+public class MultipleSQLExecution {
+
+    private Connection connection;
+
+    public MultipleSQLExecution(Connection connection) {
+        this.connection = connection;
+    }
+
+    public boolean executeMultipleStatements() throws SQLException {
+        String sql = "INSERT INTO users (name, email) VALUES ('Alice', '[email protected]');" +
+                     "INSERT INTO users (name, email) VALUES ('Bob', '[email protected]');";
+
+        try (Statement statement = connection.createStatement()) {
+            statement.execute(sql);
+            return true;
+        }
+    }
+
+    public int[] executeBatchProcessing() throws SQLException {
+        try (Statement statement = connection.createStatement()) {
+            connection.setAutoCommit(false);
+
+            statement.addBatch("INSERT INTO users (name, email) VALUES ('Charlie', '[email protected]')");
+            statement.addBatch("INSERT INTO users (name, email) VALUES ('Diana', '[email protected]')");
+
+            int[] updateCounts = statement.executeBatch();
+            connection.commit();
+
+            return updateCounts;
+        }
+    }
+
+    public boolean callStoredProcedure() throws SQLException {
+        try (CallableStatement callableStatement = connection.prepareCall("{CALL InsertMultipleUsers()}")) {
+            callableStatement.execute();
+            return true;
+        }
+    }
+    
+    public List<User> executeMultipleSelectStatements() throws SQLException {
+        String sql = "SELECT * FROM users WHERE email = '[email protected]';" +
+                     "SELECT * FROM users WHERE email = '[email protected]';";
+
+        List<User> users = new ArrayList<>();
+
+        try (Statement statement = connection.createStatement()) {
+            statement.execute(sql); // Here we execute the multiple queries
+
+            do {
+                try (ResultSet resultSet = statement.getResultSet()) {
+                    while (resultSet != null && resultSet.next()) {
+                        int id = resultSet.getInt("id");
+                        String name = resultSet.getString("name");
+                        String email = resultSet.getString("email");
+                        users.add(new User(id, name, email));
+                    }
+                }
+            } while (statement.getMoreResults());
+
+        }
+        return users;
+    }
+}

persistence-modules/core-java-persistence-4/src/main/java/com/baeldung/sql/User.java

@@ -0,0 +1,38 @@
+package com.baeldung.sql;
+
+public class User {
+    private int id;
+    private String name;
+    private String email;
+
+    public User(int id, String name, String email) {
+        this.id = id;
+        this.name = name;
+        this.email = email;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+}
+

persistence-modules/core-java-persistence-4/src/test/java/com/baeldung/sql/MultipleSQLExecutionLiveTest.java

@@ -0,0 +1,92 @@
+package com.baeldung.sql;
+
+import org.junit.Before;
+import org.junit.jupiter.api.Test;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.assertj.core.api.Assertions.assertThat;
+
+// Please note, this test requires a MySQL server running on localhost:3306 with database users_db already created.
+// We have added creation of the table it in the setup() method.
+public class MultipleSQLExecutionLiveTest {
+
+    private static Connection connection;
+    
+    @Before
+    public void setup() throws ClassNotFoundException, SQLException {
+        Class.forName("com.mysql.cj.jdbc.Driver");
+        String url = "jdbc:mysql://localhost:3306/user_db?allowMultiQueries=true";
+        String username = "username";
+        String password = "password";
+        connection = DriverManager.getConnection(url, username, password);
+            
+        Statement statement = connection.createStatement();
+        String createUsersSql = "CREATE TABLE users ( id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(50) NOT NULL, email VARCHAR(100) NOT NULL UNIQUE );";
+        statement.execute(createUsersSql);
+    }
+
+    @Test
+    public void givenMultipleStatements_whenExecuting_thenRecordsAreInserted() throws SQLException {       
+        MultipleSQLExecution execution = new MultipleSQLExecution(connection);
+        boolean result = execution.executeMultipleStatements();
+        assertTrue(result, "The statements should execute successfully.");
+
+        try (Statement statement = connection.createStatement();
+             ResultSet resultSet = statement.executeQuery("SELECT COUNT(*) AS count FROM users WHERE name IN ('Alice', 'Bob')")) {
+            resultSet.next();
+            int count = resultSet.getInt("count");
+            assertEquals(2, count, "Two records should have been inserted.");
+        }
+    }
+
+    @Test
+    public void givenBatchProcessing_whenExecuting_thenRecordsAreInserted() throws SQLException {
+        MultipleSQLExecution execution = new MultipleSQLExecution(connection);
+        int[] updateCounts = execution.executeBatchProcessing();
+        assertEquals(2, updateCounts.length, "Batch processing should execute two statements.");
+
+        try (Statement statement = connection.createStatement();
+             ResultSet resultSet = statement.executeQuery("SELECT COUNT(*) AS count FROM users WHERE name IN ('Charlie', 'Diana')")) {
+            resultSet.next();
+            int count = resultSet.getInt("count");
+            assertEquals(2, count, "Two records should have been inserted via batch.");
+        }
+    }
+
+    @Test
+    public void givenStoredProcedure_whenCalling_thenRecordsAreInserted() throws SQLException {
+        MultipleSQLExecution execution = new MultipleSQLExecution(connection);
+        boolean result = execution.callStoredProcedure();
+        assertTrue(result, "The stored procedure should execute successfully.");
+
+        try (Statement statement = connection.createStatement();
+             ResultSet resultSet = statement.executeQuery("SELECT COUNT(*) AS count FROM users WHERE name IN ('Eve', 'Frank')")) {
+            resultSet.next();
+            int count = resultSet.getInt("count");
+            assertEquals(2, count, "Stored procedure should have inserted two records.");
+        }
+    }
+    
+    @Test
+    public void givenMultipleSelectStatements_whenExecuting_thenCorrectUsersAreFetched() throws SQLException {
+        MultipleSQLExecution execution = new MultipleSQLExecution(connection);
+        execution.executeMultipleStatements();
+
+        List<User> users = execution.executeMultipleSelectStatements();
+
+        // Here we verify that exactly two users are fetched and their names match the expected ones
+        assertThat(users)
+            .hasSize(2)
+            .extracting(User::getName)
+            .containsExactlyInAnyOrder("Alice", "Bob");
+    }
+}
+