A Table can have a Composite Primary Key which is a primary key made from two or more columns. For example: CREATE TABLE userdata ( userid INT, userdataid INT, info char(200), primary key (userid, userdataid) ); Update: Here is a link with a more detailed description of composite primary keys.
I just queried my database with millions of customers in the USA. The maximum first name length was 46. I go with 50. (Of course, only 500 of those were over 25, and they were all cases where data imports resulted in extra junk winding up in that field.) Last name was similar to first … Read more
There are ways of doing this in optional parts of the standard, but a lot of databases support their own way of doing it. A really good site that talks about this and other things is http://troels.arvin.dk/db/rdbms/#select-limit. Basically, PostgreSQL and MySQL supports the non-standard: SELECT… LIMIT y OFFSET x Oracle, DB2 and MSSQL supports the … Read more
Either connect to node instance and use shutdown command or if you are on ubuntu you can try to restart redis server through init.d: /etc/init.d/redis-server restart or stop/start it: /etc/init.d/redis-server stop /etc/init.d/redis-server start On Mac redis-cli shutdown
The SQLite command line utility has a .schema TABLENAME command that shows you the create statements.
All solutions I found were much more complex than necessary and none worked for me. Here is the solution that solved my problem. There isn’t any need to restart mysqld or start it with special privileges. sudo mysql — for MySQL ALTER USER ‘root’@’localhost’ IDENTIFIED WITH mysql_native_password BY ‘root’; — for MariaDB ALTER USER ‘root’@’localhost’ … Read more
It’s working as intended. Your MySQL server has been started with –secure-file-priv option which limits from which directories you can load files using LOAD DATA INFILE. Use SHOW VARIABLES LIKE “secure_file_priv”; to see the directory that has been configured. You have two options: Move your file to the directory specified by secure-file-priv. Disable secure-file-priv. This … Read more
I’m the CTO of 10gen (developers of MongoDB) so I’m a bit biased, but I also manage a few sites that are using MongoDB in production. businessinsider has been using mongo in production for over a year now. They are using it for everything from users and blog posts, to every image on the site. … Read more
In the build.gradle file for your app module, add this to the defaultConfig section (under the android section). This will write out the schema to a schemas subfolder of your project folder. javaCompileOptions { annotationProcessorOptions { arguments += [“room.schemaLocation”: “$projectDir/schemas”.toString()] } } Like this: // … android { // … (compileSdkVersion, buildToolsVersion, etc) defaultConfig { … Read more
The basic idea is that you have two numbers to make up a primary key- a “high” number and a “low” number. A client can basically increment the “high” sequence, knowing that it can then safely generate keys from the entire range of the previous “high” value with the variety of “low” values. For instance, … Read more