Databases
Generally, all apps use a database to persist data.
Either for the running of the app (quartz scheduler),
for storing information to perform some logic later on,
for storing information to record workflow, or
audit information of a workflow for reporting purposes
What
Types
Relational Databases
NoSQL
Key Understandings behind databases
These facts about computers influence the design of databases:
You cannot do much with data on disk until you read it to memory.
You cannot do much with data in memory until you read it to the CPU cache and registers.
Reading from disk (SSD) is 2000 times slower than reading from memory.
Reading from memory is 200 times slower than reading from the CPU cache (L1d)
Disk is limited.
Memory is scarce.
CPU caches are scarcer.
If you read a chunk of bytes to memory, use it fully, Or else some other chunk will take its place.
If you read a chunk of bytes to the CPU try to use it fully. Or else some other chunk will take its place.
Areas
SQL commands
Queries
select
http://www.java67.com/2018/02/why-you-should-not-use-select-in-sql.html
joins
where
alias
Inserts
update
Delete
rows
users
cascade
Table creation
Foreign keys
primary keys
composite keys
junctions
combining
one - one
one - many
many - many
constraints
indexes
https://8thlight.com/blog/kyle-annen/2018/10/09/an-introduction-to-database-indexing.html
tablespaces
partitions
by reference
links
https://www.oracle-dba-online.com/sql/oracle_sql_tutorial.htm
https://www.w3schools.com/sql/
https://www.tutorialspoint.com/oracle_sql/index.asp
PL/SQL
Links
http://dba.fyicenter.com/faq/oracle/oracle_introduction_pl_sql.html
https://www.tutorialspoint.com/plsql/index.htm
http://plsql-tutorial.com/
http://www.plsqltutorial.com/
http://dba.fyicenter.com/faq/oracle/oracle_pl_sql_working_with_procedure.html
http://dba.fyicenter.com/faq/oracle/oracle_pl_sql_working_with_database_objects.html
http://dba.fyicenter.com/faq/oracle/oracle_pl_sql_working_with_cursors.html
Users, permissions
Editioning and views
https://oracle-base.com/articles/11g/edition-based-redefinition-11gr2
Cross edition triggers
https://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:2076251000346161474
Oracle developer GUI
worksheets
connecting to databases
search through tables
ordering in tables
Viewing views
Must set edition to see the views
Links
http://www.oracle.com/technetwork/developer-tools/sql-developer/getting-started-155046.html
http://www.devshed.com/c/a/oracle/how-to-use-the-oracle-sql-developer-tool/
http://www.tutorialized.com/tutorial/Oracle-DBA-FAQ---Introduction-to-Oracle-SQL-Developer/12849
CQRS
Only perform queries and and inserts, useful for event sourcing
Datawhare housing
creating views
design
https://martinfowler.com/articles/evodb.html
http://databaserefactoring.com/SplitColumns.html
Books
Links
http://www.tutorialized.com/tutorial/Oracle-DBA-FAQ---Introduction-to-Oracle-SQL-Developer/12849
https://github.com/enkidevs/curriculum/wiki/SQL-Topic
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