I have been working as a data analyst for about 4 months now and the above is a very real question for me. The most recent way I've been taught to join is with the left join with the following example.

left join table1
on
table2.id = table1.id

left join table2
on
table3.table_id = table2.table_id

left join table4
on
table1.tablekey_id = table4.tablekey_id

Looking for the most efficient way to connect multiple tables to save time, if possible.

Thanks in Advance!

CodePudding user response：

1. If it is only two tables of same columns and same datatypes, you can use union concept to join the tables.
2. You can also join tables like this:

Tables: TableA, TableB

SELECT
    column1,
    column2,
    column3
FROM TableA, TableB
WHERE TableA.id = TableB.id;

CodePudding user response：

You could certainly use a shorter alias for the table names and table fields.

Example:
Table 1 = alias t1
tablekey_id = tkid

So then it would t1.tkid instead of having to type out table1.tablekey_id.