取得最后几条记录，sql写法

最新推荐文章于 2024-09-23 20:03:06 发布

转载最新推荐文章于 2024-09-23 20:03:06 发布 · 1.1k 阅读

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原文链接：https://my.oschina.net/u/2365397/blog/745954

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#数据库 #python

本文展示了一种使用Web SQL Database API实现离线消息存储及检索的方法。通过具体代码示例，介绍了如何创建表、插入数据，并分批次查询数据的过程。

2019独角兽企业重金招聘Python工程师标准>>>

1.本人工作中的一点心得，就不整理了，直接拷贝在此，后面借鉴

          var offsetNumber;
          var db = openDatabase('users', '1.0', 'users', 1024 * 1024 * 1024);
          //db.transaction(function (context) {
          //  //context.executeSql('DROP TABLE IF EXISTS messages');
          //  context.executeSql('CREATE TABLE IF NOT EXISTS messages (id unique, chat_type,timestamp,me,msg,other)');
          //  context.executeSql('INSERT INTO messages  VALUES (?,?,?,?,?,?)',[now,type,now,$rootScope.User_Name_test,message,username]);
          //});
          db.transaction(function (context) {
            //context.executeSql('DELETE  FROM messages');
              context.executeSql('SELECT count(id) AS CustomerNilsen FROM messages  WHERE (other=? OR (me=? AND other=?)) ', [friendName,friendName,$rootScope.User_Name_test], function (context, results) {
                //console.log(results.rows.item(0).CustomerNilsen);
                offsetNumber = results.rows.item(0).CustomerNilsen-retNumber;
                console.log('number='+retNumber+'---offsetNumber=',offsetNumber);
                context.executeSql('SELECT * FROM messages  WHERE (other=? OR (me=? AND other=?))  LIMIT ?,?  ', [friendName,friendName,$rootScope.User_Name_test,offsetNumber,retNumber], function (context, results) {
                  //context.executeSql('SELECT * FROM messages WHERE (other=? OR (me=? AND other=?)) AND id>?', [friendName,friendName,$rootScope.User_Name_test,time], function (context, results) {
                  //console.log(context)
                  console.log(results);
                  var len = results.rows.length, i;
                  //console.log('Got '+len+' rows.');
                  for (i = 0; i < len; i++){
                    //console.log('id: '+results.rows.item(i).id);
                    //console.log('chat_type: '+results.rows.item(i).chat_type);
                    //console.log('timestamp: '+results.rows.item(i).timestamp);
                    //console.log('from: '+results.rows.item(i).me);
                    //console.log('msg: '+results.rows.item(i).msg);
                    //console.log('to: '+results.rows.item(i).other);
                });
              });
          });

转载于:https://my.oschina.net/u/2365397/blog/745954