create-table

问题 I want to save some data coming from the request. for that, I created some entity classes. but why I et this exception? Error executing DDL "create table body_datum (body_datum_id integer not null, key varchar(255), value varchar(255), value_type varchar(255), primary key (body_datum_id)) engine=InnoDB" via Here are my properties. spring.datasource.url= jdbc:mysql://localhost:3306/loadtestdb?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC

问题 I want to save some data coming from the request. for that, I created some entity classes. but why I et this exception? Error executing DDL "create table body_datum (body_datum_id integer not null, key varchar(255), value varchar(255), value_type varchar(255), primary key (body_datum_id)) engine=InnoDB" via Here are my properties. spring.datasource.url= jdbc:mysql://localhost:3306/loadtestdb?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC

问题 Im revisiting my database and noticed I had some primary keys that were of type INT. This wasn't unique enough so I thought I would have a guid. I come from a microsoft sql background and in the ssms you can choose type to "uniqeidentifier" and auto increment it. In mysql however Ive found that you have to make triggers that execute on insert for the tables you want to generate a guide id for. Example: Table: CREATE TABLE `tbl_test` ( `GUID` char(40) NOT NULL, `Name` varchar(50) NOT NULL,

问题 There is a SQL table which is growing rapidly and inconsistently compared to it's intrinsic data. To make it short, there is a windows service backing up the content of .txt files in this table, the files weight from 1KB to 45KB approx. hence the nvarchar(max) column used to store the content of those text files. When running the sp_spaceused command on this table, here is the result: name rows reserved data index_size unused Files 20402 814872 KB 813416 KB 1048 KB 408 KB But when running

问题 What is the optimal size for external table partition? I am planning to partition table by year/month/day and we are getting about 2GB of data daily. 回答1: Optimal table partitioning is such that matching to your table usage scenario. Partitioning should be chosen based on: how the data is being queried (if you need to work mostly with daily data then partition by date). how the data is being loaded (parallel threads should load their own partitions, not overlapped) 2Gb is not too much even

问题 What is the optimal size for external table partition? I am planning to partition table by year/month/day and we are getting about 2GB of data daily. 回答1: Optimal table partitioning is such that matching to your table usage scenario. Partitioning should be chosen based on: how the data is being queried (if you need to work mostly with daily data then partition by date). how the data is being loaded (parallel threads should load their own partitions, not overlapped) 2Gb is not too much even

来源： https://stackoverflow.com/questions/54494066/difference-between-create-table-and-create-any-table-privileges

来源： https://stackoverflow.com/questions/58500320/is-there-a-way-to-specify-date-timestamp-format-for-the-incoming-data-within-the

问题 GreenDAO supports DaoMaster.dropAllTables() and DaoMaster.createAllTables(). I'm looking for similar functionality in RoomDB. Does RoomDB supports this functionality ?? The use-case for this functionality is, when the user tries to login with new mobile number to my app, i want to clear the data of old login number by showing a warning dialog message and allow login with new number. 回答1: Room supports dropping and creating tables only during a migration between schema versions. You can gain

问题 This is the message I'm getting ER_WRONG_VALUE_COUNT_ON_ROW: Column count doesn't match value count at row 1 This is my whole code. Where is my mistake? DROP TABLE student; CREATE TABLE employee ( emp_id INT PRIMARY KEY, first-name VARCHAR(40), birth_day DATE, sex VARCHAR(1), SALARY INT, super_id INT, branch_id INT ); CREATE TABLE branch ( branch_id INT PRIMARY KEY, branch_name VARCHAR(40), mgr_id INT, mgr_start_date DATE, FOREIGN KEY(mgr_id) REFERENCES employee(emp_id) ON DELETE SET NULL );