如何在 java 中执行复合 sql 查询？

Question

如何执行以下查询并通过准备好的语句检索结果：

INSERT INTO vcVisitors (sid) VALUES (?); SELECT LAST_INSERT_ID();

有没有办法同时执行两个语句？

我尝试执行以下操作：

Connection con = DbManager.getConnection();
PreparedStatement ps = con.PrepareStatement(
     "INSERT INTO vcVisitors (sid) VALUES (?); SELECT LAST_INSERT_ID();");
ps.setInt(1, 10);
ResultSet rs = ps.exequteQuery();
rs.next();
return rs.getInt("LAST_INSERT_ID()");

但它给了我一个错误，executeQuery 无法执行这样的查询，我还尝试将 executeQuery 替换为以下内容：

ps.execute();
rs = ps.getResultSet();

但它给了我 SQL 语法错误：

You have an error in your SQL syntax; 
check the manual that corresponds to your MySQL server version 
for the right syntax to use near 'SELECT LAST_INSERT_ID()' at line 1

但执行查询“INSERT INTO vcVisitors (sid) VALUES ('10'); SELECT LAST_INSERT_ID();”没有问题直接从 mysql 控制台。

Answer 1

更新（插入）数据时使用executeUpdate而不是executeQuery 。 尝试执行SELECT LAST_INSERT_ID()作为另一个查询。

但它不是便携式查询。 我建议改用Statement.getGeneratedKeys 。 请看这里： JDBC (MySQL) Retrieving AUTO_INCREMENT Column Values 。

以下是正确使用 LAST_INSERT_ID() 的示例：

    Statement stmt = null;
   ResultSet rs = null;

   try {

    //
    // Create a Statement instance that we can use for
    // 'normal' result sets.

    stmt = conn.createStatement();

    //
    // Issue the DDL queries for the table for this example
    //

    stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
    stmt.executeUpdate(
            "CREATE TABLE autoIncTutorial ("
            + "priKey INT NOT NULL AUTO_INCREMENT, "
            + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

    //
    // Insert one row that will generate an AUTO INCREMENT
    // key in the 'priKey' field
    //

    stmt.executeUpdate(
            "INSERT INTO autoIncTutorial (dataField) "
            + "values ('Can I Get the Auto Increment Field?')");

    //
    // Use the MySQL LAST_INSERT_ID()
    // function to do the same thing as getGeneratedKeys()
    //

    int autoIncKeyFromFunc = -1;
    rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

    if (rs.next()) {
        autoIncKeyFromFunc = rs.getInt(1);
    } else {
        // throw an exception from here
    }

    rs.close();

    System.out.println("Key returned from " +
                       "'SELECT LAST_INSERT_ID()': " +
                       autoIncKeyFromFunc);

} finally {

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException ex) {
            // ignore
        }
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException ex) {
            // ignore
        }
    }
}

这里与 getGeneratedKeys 相同：

     Statement stmt = null;
   ResultSet rs = null;

   try {

    //
    // Create a Statement instance that we can use for
    // 'normal' result sets assuming you have a
    // Connection 'conn' to a MySQL database already
    // available

    stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                java.sql.ResultSet.CONCUR_UPDATABLE);

    //
    // Issue the DDL queries for the table for this example
    //

    stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
    stmt.executeUpdate(
            "CREATE TABLE autoIncTutorial ("
            + "priKey INT NOT NULL AUTO_INCREMENT, "
            + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

    //
    // Insert one row that will generate an AUTO INCREMENT
    // key in the 'priKey' field
    //

    stmt.executeUpdate(
            "INSERT INTO autoIncTutorial (dataField) "
            + "values ('Can I Get the Auto Increment Field?')",
            Statement.RETURN_GENERATED_KEYS);

    //
    // Example of using Statement.getGeneratedKeys()
    // to retrieve the value of an auto-increment
    // value
    //

    int autoIncKeyFromApi = -1;

    rs = stmt.getGeneratedKeys();

    if (rs.next()) {
        autoIncKeyFromApi = rs.getInt(1);
    } else {

        // throw an exception from here
    }

    rs.close();

    rs = null;

    System.out.println("Key returned from getGeneratedKeys():"
        + autoIncKeyFromApi);
} finally {

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException ex) {
            // ignore
        }
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException ex) {
            // ignore
        }
    }
}

Answer 2

正如其他人已经说过的那样，这行不通。 但看起来您只想获取最后插入的 ID。 为此，您可以使用Statement class 的getGeneratedKeys()方法。

Answer 3

尝试：

Connection con = DbManager.getConnection();
int lastid = 0;

PreparedStatement psInsert = con.PrepareStatement(
     "INSERT INTO vcVisitors (sid) VALUES (?)");
psInsert.setInt(1, 10);
psInsert.executeUpdate();

PreparedStatement psSelect = 
    con.PrepareStatement("SELECT LAST_INSERT_ID() AS lastid");
ResultSet rs = psSelect.executeQuery();
rs.next();

lastid = rs.getInt("lastid");

rs.close();
psInsert.close();
psSelect.close();
con.close();
return lastid;