Left outer join vs left join

Is left-join faster then inner join? Does join mean the same as inner join? What is inner and LEFT OUTER JOIN? There is a notable difference where left join and left outer join used when using Microsoft SQL server. All in all, use of the left join or left outer join statement refers to the exact same statement.

Since there is no difference, the use of the left outer join is recommended. There is actually no difference between a left join and a left outer join – they both refer to the exact same operation in SQL. An example will help clear this up.

The key on the is subtle, but very important. Initially, it applies inner join on Table_A and Table_B to retrieve matching tuples from both the tables. Then it extends those tuples of Table_A with NULL that do not have a matching tuple in Table_B. OUTER JOIN are of types: LEFT OUTER JOIN - fetches data if present in the left table.

FULL OUTER JOIN - fetches data if present in either of the two tables. Are left outer joins and left joins the. Left Join vs Left Outer Join In SQL server, the keyword outer is optional when you apply left outer join. The SQL above will give us the result set shown below.

Remember that the left table is referring to the table in the FROM clause, and the right table is the table that is after the join clause. In this excerpt from SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL, John L. Viescas and Michael J. Hernandez discuss the LEFT OUTER JOIN vs. SQL OUTER JOIN – left outer join. RIGHT OUTER JOIN and offer tips on how to use each of them in SQL statements. Suppose, we want to join two tables: A and B. It means the result of the SQL left join always contains the rows in the left table.

SQL left outer join returns all rows in the left table (A) and all the matching rows found in the right table (B). Left join will return all the rows from the left table and matching rows from right table. In case of no match with right side table it will return NULL value. Left Join ” and “ Left Outer Join ” are used interchangeably because records which are returned will be the same with either of these. The SQL LEFT OUTER JOIN is the types of the outer join to combine the two tables.

It combines the two table but prefer the rows of the first table and add all the rows from the first table to the resulted table. An outer join returns a set of records (or rows) that include what an inner join would return but also includes other rows for which no corresponding match is found in the other table. For the same query if i use Outer Apply, query output will be faster but in some DBs Outer Apply takes log period for returning details.

SQLite LEFT JOIN or LEFT OUTER JOIN : The Left Join or Left Outer Join operation takes two relations, A and B, and returns the inner join of A and B along with the unmatched rows of A. This tutorial explains LEFT OUTER JOIN or LEFT JOIN and uses in SQLite. The PostgreSQL LEFT JOIN joins two tables and fetches rows based on a condition, which is matching in both tables and the unmatched rows will also be available from the table written before the JOIN clause. There are three types of outer joins , left , right and full. Joins come in three main groups – inner join , cross join and outer join.

A right join displays all rows from the right of the table. A left outer join displays all the rows from the left of the table. Alternating the SQL sequence can eliminate use of both right and left outer joins and instead use only one.

I just came across APPLY in SQL and loved how it solves query problems for so many cases, Many of the tables I was using left join to get the result, I was able to get in outer apply.