入门SQL:从基础到实践

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"BEGINNING SQL — Paul Wilton 和 John W. Colby" 《 Beginning SQL》这本书是为初学者设计的,旨在引导读者从零基础开始学习数据库和SQL语言。作者Paul Wilton和John W. Colby确保了这本书内容覆盖了数据库设计、创建第一个数据库以及理解如何在数据库中使用SQL语言等全方位的知识,无需读者事先具备相关的数据库或SQL知识。 SQL(Structured Query Language,结构化查询语言)是用于管理关系数据库的标准语言,包括数据的增、删、改、查(CRUD)操作。在本书中,读者将了解到: 1. **数据库基础**:首先会介绍什么是数据库,以及数据库在信息存储和管理中的作用。这包括了解关系型数据库模型,如实体-关系(E-R)模型,以及数据库管理系统(DBMS)的基本概念。 2. **数据库设计**:这部分会深入讲解如何设计数据库,包括需求分析、表的设计、数据类型的选择,以及如何避免数据冗余和不一致性,确保数据库的正常运行和高效性。 3. **SQL语法**:书中将详细解释SQL的基本语法,如SELECT语句用于查询数据,INSERT用于插入新记录,UPDATE用于修改现有记录,DELETE用于删除记录。此外,还会涉及JOIN操作,用于连接多个表以获取更复杂的数据。 4. **索引和视图**:索引能显著提高查询速度,而视图则是虚拟表,允许用户以特定方式查看和操作数据。这些概念在实际应用中非常关键。 5. **数据操作与控制**:书中还将介绍事务处理,确保数据的一致性和完整性。此外,还会讨论权限和角色管理,以控制对数据库的访问。 6. **高级SQL主题**:随着读者技能的提升,可能涉及到窗口函数、子查询、存储过程、触发器等更复杂的SQL特性。 7. **实际应用**:通过实例和练习,读者可以将所学知识应用于解决实际问题,比如数据库维护、数据分析和报告生成。 《Beginning SQL》是一本全面且易懂的入门教程,它不仅教会读者SQL的基础知识,还提供了丰富的实践指导,帮助读者快速上手并精通SQL语言,从而能够有效地管理和操作数据库。无论是个人兴趣学习,还是作为职业发展的基础,这本书都是一个极好的选择。

[root@zhaosai conf]# sqoop import --connect jdbc:mysql://zhaosai:3306/mydb --username root --password jqe6b6 --table news --target-dir /user/news --fields-terminated-by “;” --hive-import --hive-table news -m 1 Warning: /opt/programs/sqoop-1.4.7.bin__hadoop-2.6.0/../hbase does not exist! HBase imports will fail. Please set $HBASE_HOME to the root of your HBase installation. Warning: /opt/programs/sqoop-1.4.7.bin__hadoop-2.6.0/../hcatalog does not exist! HCatalog jobs will fail. Please set $HCAT_HOME to the root of your HCatalog installation. Warning: /opt/programs/sqoop-1.4.7.bin__hadoop-2.6.0/../accumulo does not exist! Accumulo imports will fail. Please set $ACCUMULO_HOME to the root of your Accumulo installation. Warning: /opt/programs/sqoop-1.4.7.bin__hadoop-2.6.0/../zookeeper does not exist! Accumulo imports will fail. Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation. 23/06/10 16:07:14 INFO sqoop.Sqoop: Running Sqoop version: 1.4.7 23/06/10 16:07:15 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead. 23/06/10 16:07:15 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset. 23/06/10 16:07:15 INFO tool.CodeGenTool: Beginning code generation 23/06/10 16:07:15 ERROR sqoop.Sqoop: Got exception running Sqoop: java.lang.RuntimeException: Could not load db driver class: com.mysql.jdbc.Driver java.lang.RuntimeException: Could not load db driver class: com.mysql.jdbc.Driver at org.apache.sqoop.manager.SqlManager.makeConnection(SqlManager.java:875) at org.apache.sqoop.manager.GenericJdbcManager.getConnection(GenericJdbcManager.java:59) at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:763) at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:786) at org.apache.sqoop.manager.SqlManager.getColumnInfoForRawQuery(SqlManager.java:289) at org.apache.sqoop.manager.SqlManager.getColumnTypesForRawQuery(SqlManager.java:260) at org.apache.sqoop.manager.SqlManager.getColumnTypes(SqlManager.java:246) at org.apache.sqoop.manager.ConnManager.getColumnTypes(ConnManager.java:327) at org.apache.sqoop.orm.ClassWriter.getColumnTypes(ClassWriter.java:1872) at org.apache.sqoop.orm.ClassWriter.generate(ClassWriter.java:1671) at org.apache.sqoop.tool.CodeGenTool.generateORM(CodeGenTool.java:106) at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:501) at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:628) at org.apache.sqoop.Sqoop.run(Sqoop.java:147) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:183) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:234) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:243) at org.apache.sqoop.Sqoop.main(Sqoop.java:252)

2023-06-11 上传

root@zhaosai conf]# sqoop import --connect jdbc:mysql://192.168.160.130:3306/mydb --username root -P --table news --hive-import --hive-table mydb.news --incremental append --check-column id --last-value 0 --split-by id --target-dir /hdfs://zhaosai:9000/user/hive/warehouse/news --num-mappers 1 23/06/07 17:23:56 INFO sqoop.Sqoop: Running Sqoop version: 1.4.7 Enter password: 23/06/07 17:24:04 INFO tool.BaseSqoopTool: Using Hive-specific delimiters for output. You can override 23/06/07 17:24:04 INFO tool.BaseSqoopTool: delimiters with --fields-terminated-by, etc. 23/06/07 17:24:04 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset. 23/06/07 17:24:04 INFO tool.CodeGenTool: Beginning code generation Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary. 23/06/07 17:24:04 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `news` AS t LIMIT 1 23/06/07 17:24:04 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `news` AS t LIMIT 1 23/06/07 17:24:04 INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /opt/programs/hadoop-2.7.6 注: /tmp/sqoop-root/compile/b07035b094b6ac39b87f2ef11261c934/news.java使用或覆盖了已过时的 API。 注: 有关详细信息, 请使用 -Xlint:deprecation 重新编译。 23/06/07 17:24:05 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-root/compile/b07035b094b6ac39b87f2ef11261c934/news.jar 23/06/07 17:24:05 INFO tool.ImportTool: Maximal id query for free form incremental import: SELECT MAX(`id`) FROM `news` 23/06/07 17:24:05 ERROR tool.ImportTool: Import failed: java.io.IOException: java.sql.SQLSyntaxErrorException: Unknown column 'id' in 'field list' at org.apache.sqoop.tool.ImportTool.initIncrementalConstraints(ImportTool.java:322) at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:511) at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:628) at org.apache.sqoop.Sqoop.run(Sqoop.java:147) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:183) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:234) at org.apache.sqoop.Sqoop.runTool(Sqoop.java:243) at org.apache.sqoop.Sqoop.main(Sqoop.java:252) Caused by: java.sql.SQLSyntaxErrorException: Unknown column 'id' in 'field list' at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) at com.mysql.cj.jdbc.StatementImpl.executeQuery(StatementImpl.java:1200) at org.apache.sqoop.tool.ImportTool.getMaxColumnId(ImportTool.java:238) at org.apache.sqoop.tool.ImportTool.initIncrementalConstraints(ImportTool.java:309)

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