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12.1.0 released on Sep 19, 2022

Database config file



PURPOSE:


Create database connection.

SYNTAX:


See description.


DESCRIPTION:


Vely application can use any number of databases, with each specified by a database configuration file. This file provides database name, login and connection settings and preferences.

When making a Vely project, you specify a database vendor and the database configuration file for each database your application uses (see vv), for instance:
vv ... --db="mariadb:db1 postgres:db2 sqlite:db3"  ...

in which case there are three database configuration files (db1, db2 and db3), with db1 being MariaDB, db2 being PostgreSQL and db3 being SQLite database.

You must create a database configuration file for each database your application uses, and this file must be placed with your source code. Such file will be copied to locations specified and used by Vely to connect to database(s) (see how_vely_works).

Each such file contains connection information and authentication to a database, which Vely uses to login. The names of these configuration files are used in queries. There is no limit on how many databases can be used in your application and those from different vendors can be used in the same application.

An example of database configuration file (in this case MariaDB):

[client]
user=mydbuser
password=somepwd
database=mydbname
protocol=TCP
host=127.0.0.1
port=3306


Using in your queries


Database statements that perform queries (such as run-query) must specify the database configuration file used, unless your application uses only a single database. Such configuration is given by "@<database config file>" (for instance in run-query or begin-transaction). For example, in:
run-query @mydb="select name from employees"
...
end-query

the query "myquery" is performed on a database specified by the configuration file "mydb", as in (assuming it's PostgreSQL database):
vv ... --db="postgres:mydb"  ...

You do not need to manually connect to the database; when your application uses it for the first time, a connection is automatically established, and lost connection is automatically re-established when needed.

If a database is the only one used by your application, you can omit it, as in:
run-query ="select name from employees"
...
end-query


Connection settings


The contents of a configuration file depends on the database used:

SEE ALSO:


Database ( begin-transaction   commit-transaction   current-row   database_config_file   database_queries   on-error   prepared_statements   query-result   rollback-transaction   run-query  )  SEE ALL (documentation)



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