Can we use WHERE clause in joins?

Can we use WHERE clause in joins?

To use the WHERE clause to perform the same join as you perform using the INNER JOIN syntax, enter both the join condition and the additional selection condition in the WHERE clause. The tables to be joined are listed in the FROM clause, separated by commas.

How Write outer join in MySQL?

Syntax. The syntax for the RIGHT OUTER JOIN in MySQL is: SELECT columns FROM table1 RIGHT [OUTER] JOIN table2 ON table1. column = table2.

Do we use WHERE clause in join in MySQL?

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 .

What is the difference between left join with WHERE clause & LEFT join without WHERE clause?

When you use a Left Outer join without an On or Where clause, there is no difference between the On and Where clause. Both produce the same result as in the following. First we see the result of the left join using neither an On nor a Where clause.

What is the difference between join and WHERE clause?

Rows of the outer table that do not meet the condition specified in the On clause in the join are extended with null values for subordinate columns (columns of the subordinate table), whereas the Where clause filters the rows that actually were returned to the final output.

Where clause in left outer join MySQL?

MySQL left outer join with where clause – return unmatched rows

  • pq has primary key column id.
  • pe has two-column primary key, so it may have many pqid’s or none.
  • pe.uid column has to be used to extract only relevant data ( WHERE pe.uid = “12345” )
  • should be joined to every row.

Does MySQL have outer join?

MySQL does not support full outer join out of the box, unlike other databases such as PostgreSQL, and SQL Server. So you will need to do a full outer join using a combination of other join types such as LEFT JOIN ad RIGHT JOIN that are supported in MySQL.

IS LEFT join same as left outer join?

There really is no difference between a LEFT JOIN and a LEFT OUTER JOIN. Both versions of the syntax will produce the exact same result in PL/SQL. Some people do recommend including outer in a LEFT JOIN clause so it’s clear that you’re creating an outer join, but that’s entirely optional.

What is left outer join in SQL?

A left outer join is a method of combining tables. The result includes unmatched rows from only the table that is specified before the LEFT OUTER JOIN clause. If you are joining two tables and want the result set to include unmatched rows from only one table, use a LEFT OUTER JOIN clause or a RIGHT OUTER JOIN clause.

Why we use outer join in SQL?

We use the SQL OUTER JOIN to match rows between tables. We might want to get match rows along with unmatched rows as well from one or both of the tables.

How do you give outer join in SQL?

The FULL OUTER JOIN keyword returns all records when there is a match in left (table1) or right (table2) table records.

  1. Tip: FULL OUTER JOIN and FULL JOIN are the same.
  2. Note: FULL OUTER JOIN can potentially return very large result-sets!

How can I do a FULL OUTER JOIN in MySQL?


  • LEFT OUTER Join – same as left join.
  • RIGHT OUTER Join – same as right join.
  • How to simulate full outer join in MySQL?

    – It is of the form A IS NOT NULL, where A is an attribute of any of the inner tables – It is a predicate containing a reference to an inner table that evaluates to UNKNOWN when one of its arguments is NULL – It is a conjunction containing a null-rejected condition as a conjunct – It is a disjunction of null-rejected conditions

    When to use outer join?

    Select c.CustomerName,count (o.ID)

  • from customers c
  • inner join orders o on o.CustID=c.ID
  • group by c.CustomerName
  • How to use outer join?

    Using a NOT IN statement Using an OUTER APPLY Using a LEFT OUTER JOIN Using an EXCEPT statement Using NOT EXISTS All these approaches might yield the same result, however, it is possible that one