Why Use LEFT JOIN Instead Of Inner Join?

Why use instead of join?

“JOIN” is used to retrieve data from two tables – based ON the values of a common column.

If you then want to further filter this result, use the WHERE clause.

Thus, if you want to further filter this result, specify the extra filters in the WHERE clause..

What is difference between left join and right join?

The main difference between these joins is the inclusion of non-matched rows. … The LEFT JOIN includes all records from the left side and matched rows from the right table, whereas RIGHT JOIN returns all rows from the right side and unmatched rows from the left table.

Which join is fastest?

INNER JOINWell, in general INNER JOIN will be faster because it only returns the rows matched in all joined tables based on the joined column. But LEFT JOIN will return all rows from a table specified LEFT and all matching rows from a table specified RIGHT.

Why do we need LEFT JOIN?

The LEFT JOIN clause allows you to query data from multiple tables. It returns all rows from the left table and the matching rows from the right table. If no matching rows found in the right table, NULL are used. … For each row from the T1 table, the query compares it with all the rows from the T2 table.

Is there a difference between join and inner join?

Difference between JOIN and INNER JOIN JOIN returns all rows from tables where the key record of one table is equal to the key records of another table. The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns.

Which join is faster in MySQL?

The fastest join in MySQL is the one that has indexes on all the columns specified in your where clause, the same one that doesn’t have functions like substring and concat in your where clause, the same one that uses integer columns for the join and not varchar columns in your where clause, the same one that doesn’t …

Why does LEFT JOIN return more rows?

You are getting (possible) multiple rows for each row in your left table because there are multiple matches for the join condition. If you want your total results to have the same number of rows as there is in the left part of the query you need to make sure your join conditions cause a 1-to-1 match.

Is Left join more efficient than inner join?

A LEFT JOIN is absolutely not faster than an INNER JOIN . In fact, it’s slower; by definition, an outer join ( LEFT JOIN or RIGHT JOIN ) has to do all the work of an INNER JOIN plus the extra work of null-extending the results.

Which join is faster in Hana?

From performance point of view, the Left outer join is always faster than Inner join. Inner join is usually slower due to the fact that the join is always executed.

When to use LEFT JOIN instead of inner join?

Use an inner join when you want only the results that appear in both sets. Use a left outer join when you want all the results from set a, but if set b has data relevant to some of set a’s records, then you also want to use that data in the same query too.

Is Join left or inner?

Different Types of SQL JOINs Here are the different types of the JOINs in SQL: (INNER) JOIN: Returns records that have matching values in both tables. LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table.

Which is similar to inner join?

Any INNER Join with equal as join predicate is known as Equi Join. SQL Joins are the fundamental concept of SQL similar to correlated and noncorrelated subqueries or using group by clause and a good understanding of various types of SQL join is the must for any programmer.

Is inner join default?

INNER JOIN is the default if you don’t specify the type when you use the word JOIN. You can also use LEFT OUTER JOIN or RIGHT OUTER JOIN, in which case the word OUTER is optional, or you can specify CROSS JOIN.

What is difference between Equi join and natural join?

Equi Join is a join using one common column (referred to in the “on” clause). … Natural Join is an implicit join clause based on the common columns in the two tables being joined. Common columns are columns that have the same name in both tables.

Which is faster join or subquery?

The advantage of a join includes that it executes faster. The retrieval time of the query using joins almost always will be faster than that of a subquery. By using joins, you can maximize the calculation burden on the database i.e., instead of multiple queries using one join query.