In a MySQL JOIN, what is the difference between ON and USING()? As far as I can tell, USING() is just more convenient syntax, whereas ON allows a little more flexibility when the column names are not identical.
For larger queries I would say that the first way is more readable. If you have a mix left joins and some inner joins, then it is far more consistent to have the joins condition on the join clause, rather than some in the joins and some in the where clause.
MySQL DELETE records with JOIN You generally use INNER JOIN in the SELECT statement to select records from a table that have corresponding records in other tables.
If I want to perform joins on 3 or more tables, what is the best syntax? This is my attempt: Select * from table1 inner join table2 using id1, table2 inner join table3 using id2, table3 inner ...
Use that result in Subquery and then join it with the third table and fetch it. For the very first join --> 100x100= 10000 times and suppose we get 5 matching result.
Of course, all other categories will be populated with null in the user_category_subscriptions columns. Conversely, a where clause does the join, and then reduces the rowset. So, this does all of the joins and then eliminates all rows where user_id doesn't equal 1. You're left with an inefficient way to get an inner join. Hopefully this helps!
The table_references clause lists the tables involved in the join. So multiple-table MySQL's syntax doesn't support FROM, ORDER BY or LIMIT clauses as opposed to single-table syntax.
Note that Microsoft SQL Server also supports syntax for joins in an UPDATE statement, but MySQL and Microsoft have each implemented this syntax differently. Both of them chose to extend standard SQL (which does not normally support any join syntax for UPDATE), and they did not implement the syntax in a compatible manner.
