I learned SQL close to 25 years ago. The basic skill I learned, along with some rough methodology of applying them has got me through since then.
First basic SQL works in all RDBMS platforms. I have worked on Oracle, SQLServer, Teradata,Postgres and so on.
“Select” will get you through most of the data exploration and analysis you would need to.
Basic “Select” is selecting some/ all columns from a table with an optional filter for rows.
Once you have understood important columns from a table, you are close to understanding the table.
I have some exposure to business processes and functions so maybe now things come easier but checking the data against wha the client specifies as issue/use case is a good start. Then try asking good informed questions instead of asking for an explanation of all the columns in all the tables one by one.
The next steps for a Select are
– analytic functions
Only thing you need after these is practice and enjoy.
Two things to be careful about
- make sure you include all the required conditions
- Try to put filters which reduce the rows most first. People say it doesn’t matter in modern versions but I developed it as a habit and it may be worthwhile to confirm before discarding.