MySQL allows to join tables from different databases. Postgres can only join tables inside a single database, unless using the FDW extension. Operability Due to the underlying storage engine design, Postgres has an infamous XID wraparound issue under heavy load. For MySQL, we encountered a few ...
官网地址:https://ververica.github.io/flink-cdc-connectors/ 官方定义:This project provides a set of source connectors for Apache Flink® directly ingesting changes coming from different databases using Change Data Capture(CDC)。根据FlinkCDC官方给出的定义,FlinkCDC提供一组源数据的连接器,使用变更数据捕...
Date: November 08, 2010 02:43PM I have an application where I need to join 2 MySQL databases with several tables involved. The databases *can* be on separate servers entirely, but I still need to find a way to join them. Any ideas on how to do something like that? I can't move ...
sql -- 排序SELECT*FROMtable_nameORDERBYageDESC;-- 分页SELECT*FROMtable_nameLIMIT10OFFSET20;-- 聚合函数SELECTCOUNT(*),AVG(age),SUM(age)FROMtable_name;-- 分组SELECTage,COUNT(*)FROMtable_nameGROUPBYage;-- 连接查询SELECT*FROMordersJOINcustomersONorders.customer_id=customers.id; 1. 2. 3. 4....
R(Retrieve):查询 * 查询所有数据库的名称: * show databases; * 查询某个数据库的字符集:查询某个数据库的创建语句 * show create database 数据库名称; 3. U(Update):修改* 修改数据库的字符集 * alter database 数据库名称 character set 字符集名称; 4. D(Delete):删除* 删除数据库 * drop databa...
mysqldump -u username -p --databases luck > luck_backup.sql 替换username 为你的数据库用户名,luck 为你的数据库名。 2. 查看当前排序规则 首先查看数据库、表和字段的当前排序规则,以便了解问题所在: -- 查看数据库默认排序规则 SELECT DEFAULT_COLLATION_NAME ...
mysqldump -u username -p --databases luck > luck_backup.sql 替换 username 为你的数据库用户名，luck 为你的数据库名。2. 查看当前排序规则 首先查看数据库、表和字段的当前排序规则，以便了解问题所在：-- 查看数据库默认排序规则SELECT DEFAULT_COLLATION_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_...
**from > on> join > where > group by > with > having > select(**含重命名) > distinct > order by > limit 三、Update | Delete | 插入查询结果 3.1 Update 语法: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 UPDATE table_name SET column = expr [, column = expr ...] [WHERE ...
EXPLAIN SELECT * FROM s1 INNER JOIN s2 ON s1.key1=s2.key1 WHERE s1.common_field='a'; extra:一些额外的信息。可以通过这些额外的信息来更准确的理解MySQL到底将如何执行给定的查询语句。下面是几种额外信息, No tables userd:当查询语句中没有FROM子句时将会提示该信息EXPLAIN SELECT 1; Impossible wher...
show databases; 查看表 查看编码格式 show variables like 'character%'; 存在的所有表 show tables; 创建表的命令 show create table table_name; 表的结构 show index from table_name; show columns from table_name; 注:“show columns from table_name;”和“desctable_name;”效果是一样的。