描述

java.sql.Statement接口定义了向数据库发送SQL命令，以及从数据库获取结果集的方法与属性，通过Connection::createStatement方法创建。核心作用是：

• 执行DDL语句（如CREATE TABLE、ALTER TABLE）、DML语句（如INSERT、UPDATE）、DQL语句（如SELECT）。
• 返回SQL执行结果（查询结果集ResultSet、受影响行数）。
• 提供批量执行SQL、设置查询超时等辅助功能。

详细接口说明请参考JDBC官方网站 (opens new window)。

方法

YashanDB JDBC驱动对Statement接口有如下方法：

方法	返回类型
executeQuery(String sql)	ResultSet
executeUpdate(String sql)	int
close()	void
setMaxFieldSize(int max)	void
getMaxFieldSize()	int
setMaxRows(int max)	void
getMaxRows()	int
execute(String sql)	boolean
addBatch( String sql )	void
clearBatch()	void
executeBatch()	int[]
executeLargeBatch()	long[]
getResultSet()	ResultSet
getGeneratedKeys()	ResultSet
executeUpdate(String sql, int columnIndexes[])	int
execute(String sql, int columnIndexes[])	boolean
executeLargeUpdate(String sql, int columnIndexes[]);	long
executeUpdate(String sql, int autoGeneratedKeys)	int
execute(String sql, int autoGeneratedKeys)	boolean
executeLargeUpdate(String sql, int autoGeneratedKeys)	long
execute(String sql, String columnNames[])	boolean
executeLargeUpdate(String sql, String columnNames[])	long
executeUpdate(String sql, String columnNames[])	int
getUpdateCount()	int
getResultSetConcurrency()	int
getResultSetType()	int
getConnection()	Connection
getResultSetHoldability()	int
isClosed()	boolean
setPoolable(boolean poolable)	void
isPoolable()	boolean
getLargeUpdateCount() throws SQLException	long
setLargeMaxRows(long max) throws SQLException	void
getLargeMaxRows() throws SQLException	long
executeLargeUpdate(String sql) throws SQLException	long
setFetchSize(int rows)	void
getFetchSize()	int
closeOnCompletion()	void
isCloseOnCompletion()	boolean
setQueryTimeout(int seconds)	void
getQueryTimeout()	int
cancel()	void
getMoreResults()	boolean
getMoreResults(int current)	boolean
setFetchDirection(int direction)	void
getFetchDirection()	int
setCursorName(String name)	void
setEscapeProcessing(boolean enable)	void
getWarnings()	SQLWarning
clearWarnings()	void

示例

package quickstart;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class StatementExample {

    public static Connection getConnection() throws SQLException, ClassNotFoundException {
        String url = "jdbc:yasdb://192.168.1.2:1688/yasdb";
        Properties info = new Properties();
        info.setProperty("user", "username");
        info.setProperty("password", "passwd");
        Class.forName("com.yashandb.jdbc.Driver");
        return DriverManager.getConnection(url, info);
    }

    // 简单查询
    public void simpleQuery(Connection conn) throws SQLException {
        String sql = "SELECT id, name FROM users";
        try (Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery(sql)) {
            while (rs.next()) {
                System.out.println("ID: " + rs.getInt("id") +
                                   ", Name: " + rs.getString("name"));
            }
        }
    }

    // 执行DML
    public void executeUpdate(Connection conn) throws SQLException {
        String sql = "UPDATE users SET status = 'active' WHERE id = 1";
        try (Statement stmt = conn.createStatement()) {
            int rows = stmt.executeUpdate(sql);
            System.out.println("Updated rows: " + rows);
        }
    }

    // 执行多条语句
    public void executeMultiple(Connection conn) throws SQLException {
        try (Statement stmt = conn.createStatement()) {
            // 执行INSERT
            stmt.execute("INSERT INTO users (id, name, status) VALUES (102, 'Alice', 'inactive')");

            // 执行UPDATE
            int rows = stmt.executeUpdate("DELETE FROM users WHERE name = 'Bob'");
            System.out.println("Deleted rows: " + rows);

            // 执行SELECT
            try (ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM users")) {
                if (rs.next()) {
                    System.out.println("Total users: " + rs.getInt(1));
                }
            }
        }
    }

    // 批量执行
    public void batchExecution(Connection conn) throws SQLException {
        try (Statement stmt = conn.createStatement()) {
            stmt.addBatch("INSERT INTO users (id, name, status) VALUES (103, 'User1', 'inactive')");
            stmt.addBatch("INSERT INTO users (id, name, status) VALUES (104, 'User2', 'inactive')");
            stmt.addBatch("UPDATE users SET status = 'active' WHERE id > 100");

            int[] results = stmt.executeBatch();
            System.out.println("Batch executed successfully");
        }
    }

    public static void main(String[] args) {
        try (Connection conn = getConnection()) {
            try (Statement stmt = conn.createStatement()) {
                try {
                    stmt.execute("DROP TABLE users");
                } catch (SQLException ignored) {
                }
                stmt.execute("CREATE TABLE users (id INT PRIMARY KEY, name VARCHAR(20), status VARCHAR(20))");
                stmt.execute("INSERT INTO users VALUES (1, 'Alice', 'inactive')");
                stmt.execute("INSERT INTO users VALUES (2, 'Bob', 'inactive')");
                stmt.execute("INSERT INTO users VALUES (101, 'Carol', 'inactive')");
            }
            StatementExample example = new StatementExample();
            example.simpleQuery(conn);
            example.executeUpdate(conn);
            example.executeMultiple(conn);
            example.batchExecution(conn);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }
}

正常情况下，程序输出如下：

ID: 1, Name: Alice
ID: 2, Name: Bob
ID: 101, Name: Carol
Updated rows: 1
Deleted rows: 1
Total users: 3
Batch executed successfully