create table users_ning(id primary key auto_increment,pwd int); insert into users_ning values(id,1234);insert into users_ning values(id,12345); insert into users_ning values(id,12); insert into users_ning values(id,123);CREATEPROCEDURE login_ning(IN p_id int,IN p_pwd int,OUT flag int)BEGINDECLARE v_pwd int;select pwd INTO v_pwd from users_ningwhere id = p_id; if v_pwd = p_pwd thenset flag:=1;else select v_pwd;set flag := 0;end if;END package demo20130528;import java.sql.*;import demo20130526.DBUtils;/** * 测试JDBC API调用过程 * @author tarena * */public class ProcedureDemo2 {/** * @param args * @throws Exception*/public static void main(String[] args) throws Exception {System.out.println(login(123, 1234));}/** * 调用过程,实现登录功能 * @param id 考生id * @param pwd 考试密码 * @return if成功:1; if密码错:0; if没有用户:-1 * @throws Exception*/public static int login(int id, int pwd) throws Exception{int flag = -1;String sql = "{call login_ning(?,?,?)}";//*****Connection conn = DBUtils.getConnMySQL();CallableStatement stmt = null;try{stmt = conn.prepareCall(sql);//传递输入参数stmt.setInt(1, id);stmt.setInt(2, pwd);//注册输出参数,第三个占位符的数据类型是整型stmt.registerOutParameter(3, Types.INTEGER);//*****//执行过程stmt.execute();//获得过程执行后的输出参数flag = stmt.getInt(3);//*****}catch(Exception e){e.printStackTrace();}finally{stmt.close();DBUtils.dbClose();}return flag;}}
package demo20130526;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.sql.Connection;import java.sql.DatabaseMetaData;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;public class DBUtils {<span style="white-space:pre"> </span>static Connection conn = null;<span style="white-space:pre"> </span>static PreparedStatement stmt = null;<span style="white-space:pre"> </span>static ResultSet rs = null;<span style="white-space:pre"> </span>static Statement st = null;<span style="white-space:pre"> </span>static String username = null;<span style="white-space:pre"> </span>static String password = null;<span style="white-space:pre"> </span>static String url = null;<span style="white-space:pre"> </span>static String driverName = null;<span style="white-space:pre"> </span>public static Connection getConnMySQL() throws Exception {// 连接mysql 返回conn<span style="white-space:pre"> </span>getUrlUserNamePassWordClassNameMySQL();<span style="white-space:pre"> </span>conn = DriverManager.getConnection(url, username, password);<span style="white-space:pre"> </span>// conn.setAutoCommit(false);设置自动提交为false<span style="white-space:pre"> </span>return conn;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static Connection getConnORCALE() throws Exception {// 连接orcale<span style="white-space:pre"> </span>// 返回conn<span style="white-space:pre"> </span>getUrlUserNamePassWordClassNameORCALE();<span style="white-space:pre"> </span>conn = DriverManager.getConnection(url, username, password);<span style="white-space:pre"> </span>// conn.setAutoCommit(false);<span style="white-space:pre"> </span>return conn;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>private static void getUrlUserNamePassWordClassNameORCALE()<span style="white-space:pre"> </span>throws Exception {<span style="white-space:pre"> </span>// 从资源文件 获取 orcale的username password url等信息<span style="white-space:pre"> </span>Properties pro = new Properties();<span style="white-space:pre"> </span>File path = new File("src/all.properties");<span style="white-space:pre"> </span>pro.load(new FileInputStream(path));<span style="white-space:pre"> </span>String paths = pro.getProperty("filepath");<span style="white-space:pre"> </span>File file = new File(paths + "orcale.properties");<span style="white-space:pre"> </span>getFromProperties(file);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getUrlUserNamePassWordClassNameMySQL() throws Exception {<span style="white-space:pre"> </span>// 从资源文件 获取mysql的username password url等信息<span style="white-space:pre"> </span>Properties pro = new Properties();<span style="white-space:pre"> </span>File path = new File("src/all.properties");<span style="white-space:pre"> </span>pro.load(new FileInputStream(path));<span style="white-space:pre"> </span>String paths = pro.getProperty("filepath");<span style="white-space:pre"> </span>File file = new File(paths + "mysql.properties");<span style="white-space:pre"> </span>getFromProperties(file);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getFromProperties(File file) throws IOException,<span style="white-space:pre"> </span>FileNotFoundException, ClassNotFoundException {// 读资源文件的内容<span style="white-space:pre"> </span>Properties pro = new Properties();<span style="white-space:pre"> </span>pro.load(new FileInputStream(file));<span style="white-space:pre"> </span>username = pro.getProperty("username");<span style="white-space:pre"> </span>password = pro.getProperty("password");<span style="white-space:pre"> </span>url = pro.getProperty("url");<span style="white-space:pre"> </span>driverName = pro.getProperty("driverName");<span style="white-space:pre"> </span>Class.forName(driverName);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void dbClose() throws Exception {// 关闭所有<span style="white-space:pre"> </span>if (rs != null)<span style="white-space:pre"> </span>rs.close();<span style="white-space:pre"> </span>if (st != null)<span style="white-space:pre"> </span>st.close();<span style="white-space:pre"> </span>if (stmt != null)<span style="white-space:pre"> </span>stmt.close();<span style="white-space:pre"> </span>if (conn != null)<span style="white-space:pre"> </span>conn.close();<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static ResultSet getById(String tableName, int id) throws Exception {// 用id来查询结果<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>rs = st.executeQuery("select * from " + tableName + "where id=" + id<span style="white-space:pre"> </span>+ " ");<span style="white-space:pre"> </span>return rs;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static ResultSet getByAll(String sql, Object... obj)<span style="white-space:pre"> </span>throws Exception {// 用关键字 实现查询 关键字额可以任意<span style="white-space:pre"> </span>sql = sql.replaceAll(";", "");<span style="white-space:pre"> </span>sql = sql.trim();<span style="white-space:pre"> </span>stmt = conn.prepareStatement(sql);<span style="white-space:pre"> </span>String[] strs = sql.split("//?");// 将sql 以? 非开<span style="white-space:pre"> </span>int num = strs.length;// 得到?的个数<span style="white-space:pre"> </span>int size = obj.length;<span style="white-space:pre"> </span>for (int i = 1; i stmt.setObject(i, obj[i - 1]);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>if (size for (int k = size + 1; k stmt.setObject(k, null);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>rs = stmt.executeQuery();<span style="white-space:pre"> </span>return rs;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void doInsert(String sql) throws SQLException {// 传入 sql 语句<span style="white-space:pre"> </span>// 实现插入操作<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>st.execute(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void doInsert(String sql, Object... args) throws Exception {// 传入参数<span style="white-space:pre"> </span>// 利用<span style="white-space:pre"> </span>// PreparedStatement<span style="white-space:pre"> </span>// 实现插入<span style="white-space:pre"> </span>// 传入的参数是任意多个 因为有Object 。。。args<span style="white-space:pre"> </span>int size = args.length;// 获得 Object ...obj 传过来的参数的个数<span style="white-space:pre"> </span>stmt = conn.prepareStatement(sql);<span style="white-space:pre"> </span>for (int i = 1; i stmt.setObject(i, args[i - 1]);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>stmt.execute();<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static int doUpdate(String sql) throws Exception {// 传入 sql 实现更新操作<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>int num = st.executeUpdate(sql);<span style="white-space:pre"> </span>return num;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void doUpdate(String sql, Object... obj) throws Exception {<span style="white-space:pre"> </span>// 传入参数 利用 PreparedStatement实现更新<span style="white-space:pre"> </span>// 传入的参数是任意多个 因为有Object 。。。args<span style="white-space:pre"> </span>int size = obj.length;// 获得 Object ...obj 传过来的参数的个数<span style="white-space:pre"> </span>stmt = conn.prepareStatement(sql);<span style="white-space:pre"> </span>for (int i = 1; i stmt.setObject(i, obj[i - 1]);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>stmt.executeUpdate(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static boolean doDeleteById(String tableName, int id)<span style="white-space:pre"> </span>throws SQLException {// 删除记录 by id<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>boolean b = st.execute("delete from " + tableName + " where id=" + id<span style="white-space:pre"> </span>+ "");<span style="white-space:pre"> </span>return b;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static boolean doDeleteByAll(String sql, Object... args)<span style="white-space:pre"> </span>throws SQLException {// 删除记录 可以按任何关键字<span style="white-space:pre"> </span>sql = sql.replaceAll(";", "");<span style="white-space:pre"> </span>sql = sql.trim();<span style="white-space:pre"> </span>stmt = conn.prepareStatement(sql);<span style="white-space:pre"> </span>String[] strs = sql.split("//?");// 将sql 以? 非开<span style="white-space:pre"> </span>int num = strs.length;// 得到?的个数<span style="white-space:pre"> </span>int size = args.length;<span style="white-space:pre"> </span>for (int i = 1; i stmt.setObject(i, args[i - 1]);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>if (size for (int k = size + 1; k stmt.setObject(k, null);// 数组下标从0开始<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>boolean b = stmt.execute();<span style="white-space:pre"> </span>return b;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getMetaDate() throws Exception {// 获取数据库元素数据<span style="white-space:pre"> </span>conn = DBUtils.getConnORCALE();<span style="white-space:pre"> </span>DatabaseMetaData dmd = conn.getMetaData();<span style="white-space:pre"> </span>System.out.println(dmd.getDatabaseMajorVersion());<span style="white-space:pre"> </span>System.out.println(dmd.getDatabaseProductName());<span style="white-space:pre"> </span>System.out.println(dmd.getDatabaseProductVersion());<span style="white-space:pre"> </span>System.out.println(dmd.getDatabaseMinorVersion());<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static String[] getColumnNamesFromMySQL(String sql) throws Exception {<span style="white-space:pre"> </span>conn = DBUtils.getConnMySQL();<span style="white-space:pre"> </span>return getColumnName(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static String[] getColumnNamesFromOrcale(String sql)<span style="white-space:pre"> </span>throws Exception {<span style="white-space:pre"> </span>conn = DBUtils.getConnORCALE();<span style="white-space:pre"> </span>return getColumnName(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>private static String[] getColumnName(String sql) throws Exception {// 返回表中所有的列名<span style="white-space:pre"> </span>conn = DBUtils.getConnORCALE();<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>rs = st.executeQuery(sql);<span style="white-space:pre"> </span>ResultSetMetaData rsmd = rs.getMetaData();<span style="white-space:pre"> </span>int num = rsmd.getColumnCount();<span style="white-space:pre"> </span>System.out.println("ColumnCount=" + num);<span style="white-space:pre"> </span>String[] strs = new String[num];<span style="white-space:pre"> </span>// 显示列名<span style="white-space:pre"> </span>for (int i = 1; i String str = rsmd.getColumnName(i);<span style="white-space:pre"> </span>strs[i - 1] = str;<span style="white-space:pre"> </span>System.out.print(str + "/t");<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>return strs;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getColumnDataFromMySQL(String sql) throws Exception {// 输出表中的数据<span style="white-space:pre"> </span>conn = DBUtils.getConnMySQL();<span style="white-space:pre"> </span>getColumnData(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getColumnDataFromORCALEL(String sql) throws Exception {// 输出表中的数据<span style="white-space:pre"> </span>conn = DBUtils.getConnORCALE();<span style="white-space:pre"> </span>getColumnData(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getColumnData(String sql) throws Exception {// 输出表中的数据<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>rs = st.executeQuery(sql);<span style="white-space:pre"> </span>ResultSetMetaData rsmd = rs.getMetaData();<span style="white-space:pre"> </span>System.out<span style="white-space:pre"> </span>.println("/n------------------------------------------------------------------------------------------------------------------------");<span style="white-space:pre"> </span>while (rs.next()) {<span style="white-space:pre"> </span>for (int i = 1; i System.out.print(rs.getString(i) + "/t");<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>System.out.println();<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>System.out<span style="white-space:pre"> </span>.println("------------------------------------------------------------------------------------------------------------------------");<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getTableDataFromOrcale(String sql) throws Exception {// 输出表的列名<span style="white-space:pre"> </span>// 和表中的全部数据<span style="white-space:pre"> </span>conn = DBUtils.getConnORCALE();<span style="white-space:pre"> </span>getTableData(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>public static void getTableDataFromMysql(String sql) throws Exception {// 输出表的列名<span style="white-space:pre"> </span>// 和表中的全部数据<span style="white-space:pre"> </span>conn = DBUtils.getConnMySQL();<span style="white-space:pre"> </span>getTableData(sql);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>private static void getTableData(String sql) throws SQLException {<span style="white-space:pre"> </span>// getTableDataFromMysql<span style="white-space:pre"> </span>// getTableDataFromOrcale<span style="white-space:pre"> </span>st = conn.createStatement();<span style="white-space:pre"> </span>rs = st.executeQuery(sql);<span style="white-space:pre"> </span>ResultSetMetaData rsmd = rs.getMetaData();<span style="white-space:pre"> </span>int num = rsmd.getColumnCount();<span style="white-space:pre"> </span>System.out.println("ColumnCount=" + num);<span style="white-space:pre"> </span>String[] strs = new String[num];<span style="white-space:pre"> </span>// 显示列名<span style="white-space:pre"> </span>for (int i = 1; i String str = rsmd.getColumnName(i);<span style="white-space:pre"> </span>strs[i - 1] = str;<span style="white-space:pre"> </span>System.out.print(str + "/t");<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>System.out<span style="white-space:pre"> </span>.println("/n------------------------------------------------------------------------------------------------------------------------");<span style="white-space:pre"> </span>while (rs.next()) {<span style="white-space:pre"> </span>for (int i = 1; i System.out.print(rs.getString(i) + "/t");<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>System.out.println();<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>System.out<span style="white-space:pre"> </span>.println("------------------------------------------------------------------------------------------------------------------------");<span style="white-space:pre"> </span>}}

MySQL函数可用于数据处理和计算。1.基本用法包括字符串处理、日期计算和数学运算。2.高级用法涉及结合多个函数实现复杂操作。3.性能优化需避免在WHERE子句中使用函数,并使用GROUPBY和临时表。

MySQL批量插入数据的高效方法包括:1.使用INSERTINTO...VALUES语法,2.利用LOADDATAINFILE命令,3.使用事务处理,4.调整批量大小,5.禁用索引,6.使用INSERTIGNORE或INSERT...ONDUPLICATEKEYUPDATE,这些方法能显着提升数据库操作效率。

在MySQL中,添加字段使用ALTERTABLEtable_nameADDCOLUMNnew_columnVARCHAR(255)AFTERexisting_column,删除字段使用ALTERTABLEtable_nameDROPCOLUMNcolumn_to_drop。添加字段时,需指定位置以优化查询性能和数据结构;删除字段前需确认操作不可逆;使用在线DDL、备份数据、测试环境和低负载时间段修改表结构是性能优化和最佳实践。

使用EXPLAIN命令可以分析MySQL查询的执行计划。1.EXPLAIN命令显示查询的执行计划,帮助找出性能瓶颈。2.执行计划包括id、select_type、table、type、possible_keys、key、key_len、ref、rows和Extra等字段。3.根据执行计划,可以通过添加索引、避免全表扫描、优化JOIN操作和使用覆盖索引来优化查询。

子查询可以提升MySQL查询效率。1)子查询简化复杂查询逻辑,如筛选数据和计算聚合值。2)MySQL优化器可能将子查询转换为JOIN操作以提高性能。3)使用EXISTS代替IN可避免多行返回错误。4)优化策略包括避免相关子查询、使用EXISTS、索引优化和避免子查询嵌套。

在MySQL中配置字符集和排序规则的方法包括:1.设置服务器级别的字符集和排序规则:SETNAMES'utf8';SETCHARACTERSETutf8;SETCOLLATION_CONNECTION='utf8_general_ci';2.创建使用特定字符集和排序规则的数据库:CREATEDATABASEexample_dbCHARACTERSETutf8COLLATEutf8_general_ci;3.创建表时指定字符集和排序规则:CREATETABLEexample_table(idINT

要安全、彻底地卸载MySQL并清理所有残留文件,需遵循以下步骤:1.停止MySQL服务;2.卸载MySQL软件包;3.清理配置文件和数据目录;4.验证卸载是否彻底。

MySQL中重命名数据库需要通过间接方法实现。步骤如下:1.创建新数据库;2.使用mysqldump导出旧数据库;3.将数据导入新数据库;4.删除旧数据库。


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