版权声明:本文为博主原创文章,未经博主允许不得转载

在使用spark连接mysql的过程中报错了,错误如下

08:51:32.495 [main] ERROR  - Error loading factory org.apache.calcite.jdbc.CalciteJdbc41Factory
java.lang.NoClassDefFoundError: org/apache/calcite/linq4j/QueryProvider
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_144]
at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:1.8.0_144]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.8.0_144]
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[?:1.8.0_144]
at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[?:1.8.0_144]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_144]
at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_144]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_144]
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_144]
at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:1.8.0_144]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.8.0_144]
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[?:1.8.0_144]
at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[?:1.8.0_144]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_144]
at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_144]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_144]
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.8.0_144]
at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:1.8.0_144]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:1.8.0_144]
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[?:1.8.0_144]
at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[?:1.8.0_144]
at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[?:1.8.0_144]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_144]
at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_144]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_144]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_144]
at java.lang.Class.forName(Class.java:264) ~[?:1.8.0_144]
at org.apache.calcite.avatica.UnregisteredDriver.instantiateFactory(UnregisteredDriver.java:115) [calcite-avatica-1.2.0-incubating.jar:1.2.0-incubating]
at org.apache.calcite.avatica.UnregisteredDriver.createFactory(UnregisteredDriver.java:74) [calcite-avatica-1.2.0-incubating.jar:1.2.0-incubating]
at org.apache.calcite.avatica.UnregisteredDriver.<init>(UnregisteredDriver.java:55) [calcite-avatica-1.2.0-incubating.jar:1.2.0-incubating]
at org.apache.calcite.jdbc.Driver.<init>(Driver.java:53) [calcite-core-1.2.0-incubating.jar:1.2.0-incubating]
at org.apache.calcite.jdbc.Driver.<clinit>(Driver.java:49) [calcite-core-1.2.0-incubating.jar:1.2.0-incubating]
at java.lang.Class.forName0(Native Method) [?:1.8.0_144]
at java.lang.Class.forName(Class.java:348) [?:1.8.0_144]
at java.sql.DriverManager.isDriverAllowed(DriverManager.java:556) [?:1.8.0_144]
at java.sql.DriverManager.isDriverAllowed(DriverManager.java:548) [?:1.8.0_144]
at java.sql.DriverManager.getDrivers(DriverManager.java:446) [?:1.8.0_144]
at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory$1.apply(JdbcUtils.scala:52) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory$1.apply(JdbcUtils.scala:50) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD$.resolveTable(JDBCRDD.scala:58) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRelation.<init>(JDBCRelation.scala:113) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.execution.datasources.jdbc.JdbcRelationProvider.createRelation(JdbcRelationProvider.scala:45) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:330) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:152) [spark-sql_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:125) [spark-sql_2.11-2.1.0.jar:2.1.0]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:45) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:50) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:52) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:54) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:56) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:58) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw$$iw.<init>(<console>:60) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw$$iw.<init>(<console>:62) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw$$iw.<init>(<console>:64) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw$$iw.<init>(<console>:66) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw$$iw.<init>(<console>:68) [scala-library-2.11.8.jar:?]
at $line31.$read$$iw.<init>(<console>:70) [scala-library-2.11.8.jar:?]
at $line31.$read.<init>(<console>:72) [scala-library-2.11.8.jar:?]
at $line31.$read$.<init>(<console>:76) [scala-library-2.11.8.jar:?]
at $line31.$read$.<clinit>(<console>) [scala-library-2.11.8.jar:?]
at $line31.$eval$.$print$lzycompute(<console>:7) [scala-library-2.11.8.jar:?]
at $line31.$eval$.$print(<console>:6) [scala-library-2.11.8.jar:?]
at $line31.$eval.$print(<console>) [scala-library-2.11.8.jar:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_144]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_144]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_144]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_144]
at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:786) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:1047) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunReq$1.apply(IMain.scala:638) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunReq$1.apply(IMain.scala:637) [scala-compiler-2.11.8.jar:?]
at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31) [scala-reflect-2.11.8.jar:?]
at scala.reflect.internal.util.AbstractFileClassLoader.asContext(AbstractFileClassLoader.scala:19) [scala-reflect-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain$WrappedRequest.loadAndRunReq(IMain.scala:637) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:569) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:807) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:825) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:825) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:681) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.processLine(ILoop.scala:395) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:415) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:923) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:909) [scala-compiler-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:909) [scala-compiler-2.11.8.jar:?]
at scala.reflect.internal.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:97) [scala-reflect-2.11.8.jar:?]
at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:909) [scala-compiler-2.11.8.jar:?]
at org.apache.spark.repl.Main$.doMain(Main.scala:68) [spark-repl_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.repl.Main$.main(Main.scala:51) [spark-repl_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.repl.Main.main(Main.scala) [spark-repl_2.11-2.1.0.jar:2.1.0]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_144]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_144]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_144]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_144]
at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:738) [spark-core_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:187) [spark-core_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:212) [spark-core_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:126) [spark-core_2.11-2.1.0.jar:2.1.0]
at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala) [spark-core_2.11-2.1.0.jar:2.1.0]
Caused by: java.lang.ClassNotFoundException: org.apache.calcite.linq4j.QueryProvider
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_144]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[?:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_144]
... 110 more
java.lang.RuntimeException: Error loading factory org.apache.calcite.jdbc.CalciteJdbc41Factory
at org.apache.calcite.avatica.UnregisteredDriver.handle(UnregisteredDriver.java:132)
at org.apache.calcite.avatica.UnregisteredDriver.instantiateFactory(UnregisteredDriver.java:126)
at org.apache.calcite.avatica.UnregisteredDriver.createFactory(UnregisteredDriver.java:74)
at org.apache.calcite.avatica.UnregisteredDriver.<init>(UnregisteredDriver.java:55)
at org.apache.calcite.jdbc.Driver.<init>(Driver.java:53)
at org.apache.calcite.jdbc.Driver.<clinit>(Driver.java:49)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at java.sql.DriverManager.isDriverAllowed(DriverManager.java:556)
at java.sql.DriverManager.isDriverAllowed(DriverManager.java:548)
at java.sql.DriverManager.getDrivers(DriverManager.java:446)
at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory$1.apply(JdbcUtils.scala:52)
at org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$$anonfun$createConnectionFactory$1.apply(JdbcUtils.scala:50)
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD$.resolveTable(JDBCRDD.scala:58)
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRelation.<init>(JDBCRelation.scala:113)
at org.apache.spark.sql.execution.datasources.jdbc.JdbcRelationProvider.createRelation(JdbcRelationProvider.scala:45)
at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:330)
at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:152)
at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:125)
... 54 elided
Caused by: java.lang.NoClassDefFoundError: org/apache/calcite/linq4j/QueryProvider
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at org.apache.calcite.avatica.UnregisteredDriver.instantiateFactory(UnregisteredDriver.java:115)
... 71 more
Caused by: java.lang.ClassNotFoundException: org.apache.calcite.linq4j.QueryProvider
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 110 more  

连接Mysql的代码是没问题的,但是居然会报这个错误,感觉很奇怪,而且去网上搜还搜不到相关资料,难道只有我碰到这个错误?

一开始以为是mysql的连接jar包有问题,但下载到本地用java连接又可以连接得上Mysql。

这时候注意到了错误ClassNotFoundException,一般这个错误要么是包冲突,要么是包缺失,包冲突就比较恶心了,所以先排查看看会不会是包缺失的问题,在Idea中键入两个shift,在搜素框中搜素org.apache.calcite.jdbc.CalciteJdbc41Factory。找到了这个东西,再去依赖包中查看相关jar包,发现calcite相关的有三个jar包,而在spark的jar包路径下calcite相关jar包只有两个,OK,在mven上下载缺失jar包,问题解决。


如果觉得对你有帮助,不如花0.5元请作者吃颗糖,让他甜一下吧~~

记录一次spark连接mysql遇到的问题的更多相关文章

  1. spark SQL学习(spark连接 mysql)

    spark连接mysql(打jar包方式) package wujiadong_sparkSQL import java.util.Properties import org.apache.spark ...

  2. spark 连接 mysql 数据库

    在所有master和slave上也要在spark/conf/spark-conf.sh里面设置driver的classpath,解决编译找不到driver的问题 http://www.iteblog. ...

  3. EF内容记录_EF连接Mysql版本问题

    EF连接MySQL可用版本,由于EF.MySQLConnection.mysql-for-visualstudio.VS版本.MySQL.Data.MySQL.Data.Entity版本问题较花时间, ...

  4. Spark JDBC方式连接MySQL数据库

    Spark JDBC方式连接MySQL数据库 一.JDBC connection properties(属性名称和含义) 二.spark jdbc read MySQL 三.jdbc(url: Str ...

  5. 记录一次Spring boot 搭建框架连接Mysql数据库注解事务不回滚的故障

    搭建了一个新框架,使用了spring boot 替换以简化原来繁杂的spring配置,使用Spring注解管理事务,持久层使用mybatis. 连接mysql数据库完成项目的过程中发现不支持事务,因为 ...

  6. django之python3.4及以上连接mysql的一些问题记录

    首先,祭出大杀器whl https://www.lfd.uci.edu/~gohlke/pythonlibs/#mysqlclient django1.x与django2.x 在项目的写法上有一些区别 ...

  7. 使用Apache Spark 对 mysql 调优 查询速度提升10倍以上

    在这篇文章中我们将讨论如何利用 Apache Spark 来提升 MySQL 的查询性能. 介绍 在我的前一篇文章Apache Spark with MySQL 中介绍了如何利用 Apache Spa ...

  8. Spark操作MySQL,Hive并写入MySQL数据库

    最近一个项目,需要操作近70亿数据进行统计分析.如果存入MySQL,很难读取如此大的数据,即使使用搜索引擎,也是非常慢.经过调研决定借助我们公司大数据平台结合Spark技术完成这么大数据量的统计分析. ...

  9. JdbcRDD连接MySQL

    (1)添加依赖 <dependencies> <dependency> <groupId>org.apache.spark</groupId> < ...

随机推荐

  1. 项目ITP(一) 二维码

    前言 系列文章:[传送门] 上几周碌碌无为,不行啊不行啊.博客园,不知道你几时改版.老家了,我不会忘记你呢.呵呵,我也会在os,csdn更新的.每天一搏,不管有用没用. 正文 正文先有项目起步,项目中 ...

  2. IntelliJ IDEA 注册码 (秘钥)

    给大家提供一个IDEA的注册码,最晚到2018年2月到期. 如下,展开复制即可: C0FHYYCJ22-eyJsaWNlbnNlSWQiOiJDMEZIWVlDSjIyIiwibGljZW5zZWVO ...

  3. IDEA远程仓库版本回滚

    访问我的博客 使用 git 进行项目的版本控制时,肯定会遇到回滚版本的情况,回滚有两种,一种是本地仓库回滚,另外一种是远程仓库回滚.以下详细讲解两种回滚方式,本文主要讲解远程回滚,以及常见使用误区. ...

  4. Webpack中publicPath设置

    webpack中的path是当我们build的时候,输出项目打包文件的位置. webpack中的publicPath是我们打算放到web服务器下的目录,如果我们要放到网站的根目录下,那么就无需设置.如 ...

  5. 深入理解redis数据类型

    转载请注明出处:https://www.cnblogs.com/wenjunwei/p/9720033.html redis的存储模型 redis不是普通的键值对存储,它实际上是一个数据结构存储服务器 ...

  6. Python学习总结(一)—— 十分钟入门

    一.Python概要 1.1.语言简介 Python是一种解释型.面向对象.动态数据类型的高级程序设计语言,具有20多年的发展历史,成熟且稳定. 用任何编程语言来开发程序,都是为了让计算机干活,比如下 ...

  7. EF C# ToPagedList方法 The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must ……

    报错信息:The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' ...

  8. CLR via c# 值类型“不可变”

    昨天看书看到引用类型和值类型,书中讲到值类型“不可变”,如图: 看了两遍没怎么看懂,又仔细多看了几遍,说下我的理解: 比如说一个int类型有几个成员, MaxValue.MinValue的值是不可变的 ...

  9. C-Linux_定时器示例使用

    #include <stdlib.h> #include <signal.h> ; static struct itimerval oldtv; struct itimerva ...

  10. 给大家带来一些 horm的一些知识!

    1. form action 提交地址     https://www.baidu.com merhod 提交 方式post get get是在http的url上提交不加密 post加密在http 中 ...