Survey Database Design Last Update: 5/3/2015 Diagram and SQL files now available at https://github.com/durrantm/survey If you use this (top) answer or any element, please add feedback on improvements !!! This is a real classic, done by thousands. They always seems ‘fairly simple’ to start with but to be good it’s actually pretty complex. To do … Read more
You can use a check constraint e.g. constraint chk_education check (schoolName is not null or studiedAt is not null) From the manual: A check constraint is the most generic constraint type. It allows you to specify that the value in a certain column must satisfy a Boolean (truth-value) expression. Edit: Alternative to comply with Pithyless’ … Read more
Because Django does not support Postgres database schemas out of the box, in order to get this to work, use a database router. I created a test database to try this out with, here’s how to reproduce it: Create a test database with psql: CREATE USER tester WITH PASSWORD ‘lol so easy’; CREATE DATABASE multi_schema_db … Read more
The way MySQL implements the TIMESTAMP data type, it is actually storing the epoch time in the database. So you could just use a TIMESTAMP column with a default of CURRENT_TIMESTAMP and apply the UNIX_TIMESTAMP() to it if you want to display it as an int: CREATE TABLE foo( created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP … Read more
–for DB2/z select * from sysibm.systables where owner=”SCHEMA” and name like ‘%CUR%’ and type=”T”; –for DB2/LUW select * from sysibm.systables where CREATOR = ‘SCHEMA’ and name like ‘%CUR%’ and type=”T”; This will give you all the tables with CUR in them in the SCHEMA schema. See here for more details on the SYSIBM.SYSTABLES table. If … Read more
I’m with the Normalize camp. Here are a few hints to get you started: Start with a process to assign some arbitrary unique identifier to each “person”. Call this the PersonId or something like that. This identifier is called a surrogate key. The sole purpose of a surrogate key is to guarantees a 1 to … Read more
Here I copy paste some of the information that I have collected Key A key is a single or combination of multiple fields. Its purpose is to access or retrieve data rows from table according to the requirement. The keys are defined in tables to access or sequence the stored data quickly and smoothly. They … Read more
There is no default database for user. There is default database for current session. You can get it using DATABASE() function – SELECT DATABASE(); And you can set it using USE statement – USE database1; You should set it manually – USE db_name, or in the connection string.
mysqldump -u user -ppass -d olddb | mysql -u user -ppass -D newdb The new database must already exist. The -d flag in the mysqldump command prevents copying of data. There’s no space between the flag -p and the password.
I usually add ClientID to all tables and go with one database. But since the database is usually hard to scale I will also make it possible to run on different database instances for some or all clients. That way you can have a bunch of small clients in one database and the big ones … Read more