mysql 获取自增id的值的方法
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mysql 获取自增id的值的方法
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原生jdbc方式:
Statement.getGeneratedKeys()
示例:
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();//// 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 }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 }} }也有使用SELECT LAST_INSERT_ID() 注意:并發可能會出現問題。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 }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 }} }?
mybatis封裝后的配置如下:
<insert id="insert" parameterType="Post" useGeneratedKeys="true" keyProperty="id">調用
postDao.add(post);和以前一樣結果后返回1,使用post.getId()可以獲取到自增的id。
參考文獻:
【1】http://dev.mysql.com/doc/connector-j/en/connector-j-usagenotes-last-insert-id.html
【2】http://stackoverflow.com/questions/12241260/get-auto-genearated-key-for-the-inserted-record-in-mybatis
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