What type of JOIN to use

Question

What type of JOIN would I use to get table1 and table2 to be matched only once. For example, I have table1 (40 rows) and table2<

Answer 1

SELECT * FROM table1 LEFT JOIN table2 ON `table_1_primary_key` = `table_2_primary_key`

Or SELECT colname FROM table1 LEFT JOIN table2 ON table_1.colname = table_2.colname

Depending on the structure of your database