is a very powerful feature of MyBatis. It enables programmers have to write the
. MyBatis uses a powerful Dynamic
statement. Following are the OGNL based Dynamic
expressions provided when, otherwise trim where, set foreach The if Statement The most common thing to do in dynamic
is conditionally include a part of a where clause. For example −
0 码力 |
5 页 |
69.51 KB
| 1 年前 3
© 2018 Percona. 1 Peter Zaitsev Using MySQL for Distributed Database Architectures CEO, Percona PingCAP Infra Meetup, Shanghai, China, May 26, 2018 © 2018 Percona. 2 About Percona Solutions enterprises © 2018 Percona. 3 Presentation Cover Basics Why Going Distributed How to do it © 2018 Percona. 4 Distributed ? MySQL Deployment on More than one System © 2018 Percona. 5 Modern Active Users Possible 15M of Daily Active Users counting time of day skew © 2018 Percona. 8 Distributed Systems Tend To be More Complicated to Develop Against More Complicated to Operate Have
0 码力 |
67 页 |
4.10 MB
| 1 年前 3
Firebird Null Guide NULL behaviour and pitfalls in Firebird SQL Paul Vinkenoog Version 1.2, 30 June 2020 Table of Contents 1. What is NULL? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. NULL support in Firebird SQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . operations will render the entire expression NULL. This guide explores the behaviour of NULL in Firebird SQL , points out common pitfalls and shows you how to deal safely with expressions that contain NULL or
0 码力 |
69 页 |
479.63 KB
| 1 年前 3
TiDB: HBase分布式事务与SQL 实现 About me ● TiDB & Codis founder ● Golang expert ● Distributed database developer ● Currentlly, CEO and co-founder of PingCAP liuqi@pingcap.com https://github.com/pingcap/tidb Bloom Filters for real-time queries. ● Query predicate push down via server side Filters ● MVCC What did they say ? “Nothing is hotter than SQL -on-Hadoop, and now SQL -on- HBase is fast approaching equal hotness status” Form HBaseCon 2015 We want more ! SQL + Transaction(ACID) TiDB Features ● Consistent distributed transactions ○ TiDB makes your application code simple and robust
0 码力 |
34 页 |
526.15 KB
| 1 年前 3
阿里云 AnalyticDB for PostgreSQL - 打造更简单易用的Cloud SQL Data Warehouse 个人介绍 缪长风 ⚫ 2010年初加入支付宝，负责Oracle RAC和Greenplum数据仓库 ⚫ 有幸参与了Oracle RAC到 Greenplum再到Hadoop以及最终到 ODPS的架构演进工作。 ⚫ 2012年起，转至阿里巴巴大数据团队，负责Hbase/OTS业务支 构筑在线企业数据仓库。 • 应用易开发、适配 支持SQL 2003，部分兼容Oracle语法， 支持PL/SQL 存储过程，OLAP窗口函数，事务及数据库标准隔离级别 完备功能和生态，实现应用快速迁移或适配 • PB级数据秒级响应 MPP水平扩展架构，PB级数据查询秒级响应；向量化计算，及列存储智能索引，领先传统数据库引擎性能 3x； 新一代SQL 优化器，实现复杂分析语句免调优 • 支持多模分析 库内置100+ 机器学习算法库，实现数据智能探索；高性 能向量检索算法，支持视频/图像检索 以图搜图 AnalyticDB for PostgreSQL 产品架构 协调节点 OSS 分布式云存储服务 SQL Client/BI Tools 协调节点（Master Node） • 接收请求，制定分布式执行计划 计算组（Compute Groups） • 全并行分析计算 • 数据双副本存储 • 定期自动备份
0 码力 |
22 页 |
2.98 MB
| 1 年前 3
可视化查询创建工具助你创建,编辑和运行查询, 而不必担心语法和正确命令的用法。透过关键字建
议和减少重复输入相同的代码, 自动完成代码和自定义的代码段功能可让编码更加快速我们的调
试组件能快速寻找和更正 PL/SQL 和 PL/PGSQL 编码时的错误, 你可设置断点, 逐步运行程序, 查看
和修改变量值, 以及检查调用堆栈。
智能数据库设计器
使用我们的专业对象设计器创建、修改和管理所有数据库对象。精密的数据库设计和模型创建工具 提供全面的功能, 可生成大量高质的测试数据。你可以根据业务规则和约束快速创建具有参照完整
性的真实数据集。
六二
AB
强大的本地备份或
决方案和用于 MongoDump、Oracle 数据泵或 SQL Server 备份实用工具
的直观界面能引导你完成整个备份进程, 并减少发生错误的机会。为可重复的部署进序 (如数据库备
份.MapReduce 工作和芜本运行) 设轩于特定时间或日期生动运行。无论你身处何地
0 码力 |
4 页 |
4.23 MB
| 1 年前 3
'dbListResults_SQLiteConnection.R' 'dbListTables_SQLiteConnection.R' 'dbQuoteIdentifier_SQLiteConnection_SQL .R' 'dbQuoteIdentifier_SQLiteConnection_character.R' 'dbReadTable_SQLiteConnection_character.R' 'db 'dbSendQuery_SQLiteConnection_character.R' 'dbUnloadDriver_SQLiteDriver.R' 'dbUnquoteIdentifier_SQLiteConnection_SQL .R' 'dbWriteTable_SQLiteConnection_character_character.R' 'dbWriteTable_SQLiteConnection_character_data Needed for compatibility with generic. Otherwise ignored. field.types character vector of named SQL field types where the names are the names of new table’s columns. If missing, types inferred with DBI::dbDataType())
0 码力 |
16 页 |
119.52 KB
| 1 年前 3
implements a self-contained, serverless, zero-configuration, transactional SQL database engine. SQLite is the most widely deployed SQL database engine in the world. The source code for SQLite is in the public Data Manipulation Language: ........................................................ 13 DQL - Data Query Language: .................................................................. 14 SQLite Installation .............................................................................. 35 SQLite Insert Query ............................................................... 36 Syntax: .....................
0 码力 |
172 页 |
1.27 MB
| 1 年前 3
corresponds to an attribute of that record • relational databases typically use Structured Query Language (SQL ) to define, manage, and search data 2 Why use a database? • powerful: can search, filter abstract: layer of abstraction between stored data and app(s) common syntax: database programs use same SQL commands 3 Relational database • A database is a set of tables • Each table has a primary key a playlist) Rows: Fixed number of columns Tables: Variable number of rows 9 SQL • Structured Query Language (SQL ): a language for searching and updating a database – a standard syntax that is
0 码力 |
40 页 |
707.67 KB
| 1 年前 3
The SQL HandbookThe SQL Handbook Conclusion 2 Preface The SQL Handbook follows the 80/20 rule: learn in 20% of the time the 80% of a topic. In particular, the goal is to get you up to speed quickly with SQL. This Enjoy! 3 The SQL Handbook 1. Information systems, data and information 2. What is a Database? And a DBMS? 3. Do you always need a database? 4. Relational Databases 5. Introduction to SQL 6. Creating and running with SQL, starting from zero knowledge. You will learn the terms and the main ideas, what is a DBMS, how to structure a database, how to insert data into it, how to query the database. I0 码力 | 26 页 | 440.71 KB | 1 年前3