#Join together definition full

I've recently written an article on the topic: A Probably Incomplete, Comprehensive Guide to the Many Different Ways to JOIN Tables in SQL, which I'll summarise here. They (ab)use Venn diagrams, which are an inaccurate tool for visualising joins (they're much better for unions).Interestingly most other answers suffer from these two problems:

#Join together definition full

ДЎ.2: INNER-JOIN: Natural-JOIN implementation Select A.*, B.Col1, B.Col2 -But no B.ForeignKeењњolumn in SelectДЎ.3: INNER-JOIN with NON-Equi-join implementation Select *ДЇROM Table1 A INNER JOIN Table2 B On A.Pk <= B.Fk ДЇROM Table1 A1 INNER JOIN Table1 A2 On A1.Pk = A2.Fk Дў.1: OUTER JOIN (full outer join) Select *ДЇROM Table1 A FULL OUTER JOIN Table2 B On A.Pk = B.Fk ДЇROM Table1 A LEFT OUTER JOIN Table2 B On A.Pk = B.Fk ДЇROM Table1 A RIGHT OUTER JOIN Table2 B On A.Pk = B.Fk Non-Equi-Join: It is reverse of Equi-join where joining condition is uses other than equal operator(=) e.g, !=, =, >, =B. Natural-Join: It is enhanced version of Equi-Join, in which SELECT Technically, Join made by using equality-operator (=) to compare values of Primary Key of one table and Foreign Key values of another table, hence result set includes common(matched) records from both tables. Types of JOINS:Д¬oncern to RDBMS there are 5-types of joins:Д®qui-Join: Combines common records from two tables based on equality condition. JOINS are way to query the data that combined together from multiple tables simultaneously. Restrict that simply to NATURAL JOINs alone. In fact, it is true, because of the firstД¬ondition I mentioned for NATURAL JOIN.

The tables and their data whereas EQUI JOIN and THETA JOIN are onlyД¬onnected with the operators we use in the former.ДЄgain, there are many who consider NATURAL JOIN as some sort of Because INNER JOIN, OUTER JOIN etc are all connected with But I strongly believe that its a mistake and makes the Many consider both EQUI JOIN and Theta JOIN similar to INNER, OUTERД®tc JOINs. This is same as EQUI JOIN but it allows all other operators like >, = etc. They areДЇor whatever JOIN type ( INNER, OUTER, etc), if we use ONLY the equality operator (=), then we say that JOINs based on OperatorsДepending on the operator used for a JOIN clause, there can be two types of JOINs. It is not a different form of JOIN, rather it is a JOIN ( INNER, OUTER, etc) of a table to itself. Moreover, we won't need this at all (or needs the least, to be precise). The result of a CROSS JOIN will not make sense It is the Cartesian product of the two tables involved. This seems to be more of theoretical in nature and as a result (probably) most DBMSДon't even bother supporting this.

Removes duplicate columns from the result.

the JOIN is made on all the columns with the same name for equality.

Note that `OUTER JOIN` is a loosened form of `INNER JOIN`. In other words, OUTER JOIN is based on the fact that: ONLY the matching entries in ONE OF the tables (RIGHT or LEFT) or BOTH of the tables(FULL) SHOULD be listed. It returns rows from either table when the conditions are met and returns NULL value when there is no match. This JOIN combines LEFT OUTER JOIN and RIGHT OUTER JOIN. If there are no columns matching in the left table, it returns NULL values. This JOIN returns all the rows from the right table in conjunction with the matching rows from the If there are no columns matching in the right table, it returns NULL values. This join returns all the rows from the left table in conjunction with the matching rows from the The matched rows from one table and all rows in the other tableДЄll rows in all tables (it doesn't matter whether or not there is a match). In other words, JOIN isДЄ Syntactic sugar for INNER JOIN (see: Difference between JOIN and INNER JOIN). Note that a JOIN without any other JOIN keywords (like INNER, OUTER, LEFT, etc) is an INNER JOIN. In other words, INNER JOIN is based on the single fact that: ONLY the matching entries in BOTH the tables SHOULD be listed. In this kind of a JOIN, we get all records that match the condition in both tables, and records in both tables that do not match are not reported. SQL JOIN is a method to retrieve data from two or more database tables.