mysql

Finding functional dependency

由 十年热恋 提交于 2021-02-20 04:38:20
问题 How do I determine the functional dependency and the candidate key based on this case study? Course module and it can be performed by lecturer, student or visitor user. Course module consist of subject code and subject name. When admin creates course, it will store course ID, subject code, lecturer ID, course name, and ..... Students are required to enroll in the course and the course enrollment consist of registration ID, student information, date of enrollment, date of completion and....

Connecting to Docker container from host

由 别说谁变了你拦得住时间么 提交于 2021-02-20 04:37:45
问题 I just pulled and run the official Docker MySQL image and have it running locally on my machine: docker run --name mydb -e MYSQL_ROOT_PASSWORD=12345 -d mysql:5.7.11 The instructions on that screen tell you how to connect to the MySQL server (container) from inside yet another container (which is configured as a command-line client). But I have a generic JDBC fat client (SQuirreL) and am wondering how to connect to my docker container. For the JDBC connection string, I need to provide both a

Pagination in Flask using MySql

由 冷暖自知 提交于 2021-02-20 04:28:32
问题 I searched a lot about it. All the articles i get include SQLAlchemy and none of them deal with mysql. I am working with flask and i have a database in mysql and i need to display the data in pages. Like 1000 images, per page 10 so 100 pages. In mysql we can do pagination with the help of limit. And the routes can be: @app.route('/images', defaults={'page':1}) @app.route('/images/page/<int:page>') I need to ask is this all that is needed for pagination? or am i forgetting something important

Mysql视图、触发器、存储过程

由 做~自己de王妃 提交于 2021-02-20 04:19:59
视图 视图是一个虚拟表（非真实存在），其本质是【根据SQL语句获取动态的数据集，并为其命名】， 用户使用时只需使用【名称】即可获取结果集，并可以将其当作表来使用。 1、创建视图 --格式：CREATE VIEW 视图名称 AS SQL语句 CREATE VIEW v1 AS SELET nid, name FROM A WHERE nid > 4 2、删除视图 --格式：DROP VIEW 视图名称 DROP VIEW v1 3、修改视图 -- 格式：ALTER VIEW 视图名称 AS SQL语句 ALTER VIEW v1 AS SELET A.nid, B. NAME FROM A LEFT JOIN B ON A.id = B.nid LEFT JOIN C ON A.id = C.nid WHERE A.id > 2 AND C.nid < 5 4、使用视图 使用视图时，将其当作表进行操作即可，由于视图是虚拟表， 所以无法使用其对真实表进行创建、更新和删除操作，仅能做查询用。 触发器 对某个表进行【增/删/改】操作的前后如果希望触发某个特定的行为时， 可以使用触发器，触发器用于定制用户对表的行进行【增/删/改】前后的行为。 1、创建基本触发器 # 插入前 CREATE TRIGGER tri_before_insert_tb1 BEFORE INSERT ON tb1

Why sql function return count of all and single select return correct value?

由 对着背影说爱祢 提交于 2021-02-20 04:09:26
问题 I have function that will return all of rows, but I expect 0 or 1 because Sid is unique: CREATE DEFINER=`root`@`localhost` FUNCTION `IsInDatabase`(sId VARCHAR(21)) RETURNS tinyint(1) BEGIN RETURN (SELECT COUNT(Id) FROM table WHERE SId =sid); END When executed directly, SELECT COUNT(Id) FROM table WHERE SId ='87882118' will return exactly what I need: '1' or '0'. Why is my function not working properly ? 回答1: It's because MySQL is not case sensitive and so SId and sid are the same name, and it

Why sql function return count of all and single select return correct value?

由 你离开我真会死。 提交于 2021-02-20 04:08:30
问题 I have function that will return all of rows, but I expect 0 or 1 because Sid is unique: CREATE DEFINER=`root`@`localhost` FUNCTION `IsInDatabase`(sId VARCHAR(21)) RETURNS tinyint(1) BEGIN RETURN (SELECT COUNT(Id) FROM table WHERE SId =sid); END When executed directly, SELECT COUNT(Id) FROM table WHERE SId ='87882118' will return exactly what I need: '1' or '0'. Why is my function not working properly ? 回答1: It's because MySQL is not case sensitive and so SId and sid are the same name, and it

I have mysql and apache superset setup on dockers and connected by a bridge network, what will theSQLAlchemy URI be?

由 为君一笑 提交于 2021-02-20 03:49:36
问题 I pulled the official superset image: git clone https://github.com/apache/incubator-superset.git then added the MYSQL Client to requirements.txt cd incubator-superset touch ./docker/requirements-local.txt echo "mysqlclient==1.4.6" >> ./docker/requirements-local.txt docker-compose build --force-rm docker-compose up -d After which I made the MYSQL Container docker run --detach --network="incubator-superset_default" --name=vedasupersetmysql --env="MYSQL_ROOT_PASSWORD=vedashri" --publish 6603

I have mysql and apache superset setup on dockers and connected by a bridge network, what will theSQLAlchemy URI be?

由 浪子不回头ぞ 提交于 2021-02-20 03:49:18
问题 I pulled the official superset image: git clone https://github.com/apache/incubator-superset.git then added the MYSQL Client to requirements.txt cd incubator-superset touch ./docker/requirements-local.txt echo "mysqlclient==1.4.6" >> ./docker/requirements-local.txt docker-compose build --force-rm docker-compose up -d After which I made the MYSQL Container docker run --detach --network="incubator-superset_default" --name=vedasupersetmysql --env="MYSQL_ROOT_PASSWORD=vedashri" --publish 6603

Select distinct rows with max date in mysql 5.7 [duplicate]

由 浪子不回头ぞ 提交于 2021-02-20 03:49:17
问题 This question already has answers here : SQL select only rows with max value on a column [duplicate] (27 answers) Closed 7 months ago . Suppose having query SELECT c_id, id, max(date) as max_date FROM table GROUP BY c_id,updated And following result: c_id, id, max_date 1 5 2017-12-28 16:09:20 1 6 2019-12-28 16:09:20 2 7 2017-12-28 16:09:20 2 8 2019-12-28 16:09:20 I expect to get: c_id, id, max_date 1 6 2019-12-28 16:09:20 2 8 2019-12-28 16:09:20 How to achieve that in mysql 5.7? 回答1: Use a

I have mysql and apache superset setup on dockers and connected by a bridge network, what will theSQLAlchemy URI be?

由 梦想与她 提交于 2021-02-20 03:48:16
问题 I pulled the official superset image: git clone https://github.com/apache/incubator-superset.git then added the MYSQL Client to requirements.txt cd incubator-superset touch ./docker/requirements-local.txt echo "mysqlclient==1.4.6" >> ./docker/requirements-local.txt docker-compose build --force-rm docker-compose up -d After which I made the MYSQL Container docker run --detach --network="incubator-superset_default" --name=vedasupersetmysql --env="MYSQL_ROOT_PASSWORD=vedashri" --publish 6603
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