Direct database access couples you tightly to the schema. Any changes on either end affects the other. But it’s got the virtues of being simple and requiring one less network hop. A web service means better abstraction and looser coupling via one additional level of indirection. A web service can act as the single steward … Read more
Here you go. An illustrative story: http://www.simple-talk.com/opinion/opinion-pieces/bad-carma/
The main reason is to eliminate repetition of data, so for example if you had a user with multiple addresses and you stored this information in a single table the user information would be duplicated along with each address entry. Normalisation would seperate the addresses into their own table and then link the two using … Read more
Microservices offers decoupling. You must break down your application into independent domains. Each domain can have a DB. In case other MS needs to access data owned by some other microservices, they have to communicate over the network. In case you feel that there are too many dependent services and the network calls would be … Read more
A table should have a primary key so that you could identify each row uniquely with it. Technically, you can have tables without a primary key, but you’ll be breaking good database design rules.
Try SELECT * FROM SQLITE_SEQUENCE WHERE name=”TABLE”;. This will contain a field called seq which is the largest number for the selected table. Add 1 to this value to get the next ID. Also see the SQLite Autoincrement article, which is where the above info came from. Cheers!
Imagine a table that holds the TODOs of a team. If a TODO is not yet assigned to a member of the team, its user_id is NULL. If it is not NULL it is a foreign key to the users table.
You need to return a promise from the inner query in order for the outer chain to be chained with that. You also swallow any errors because you don’t rethrow them – it’s better to use .catch() for this reason because it makes it more clearer what is happening – that is what would happen … Read more
You are experiencing the classic XA 2-PC race condition. It does happen in production environments. There are 3 things coming to my mind. Last agent optimization where JDBC is the non-XA resource.(Lose recovery semantics) Have JMS Time-To-Deliver. (Deliberately Lose real time) Build retries into JDBC code. (Least effect on functionality) Weblogic has this LLR optimization … Read more
If you are using 8.1.5 and above you can use: To convert from hexadecimal to decimal: select to_number(‘AA’, ‘xx’) from dual; To convert from decimal to hexadecimal: select to_char(111, ‘xxxx’) from dual;