Which type of join returns rows from two table only if there is a match between columns in both table inner left right outer?
What is Inner Join in SQL?The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns. An SQL INNER JOIN is same as JOIN clause, combining rows from two or more tables. Show
Pictorial presentation of SQL Inner Join:
 Syntax: SELECT * FROM table1 INNER JOIN table2 ON table1.column_name = table2.column_name;OR SELECT * FROM table1 JOIN table2 ON table1.column_name = table2.column_name;The INNER JOIN in SQL joins two tables according to the matching of a certain criteria using a comparison operator. Syntax diagram - INNER JOIN Example: SQL INNER JOIN between two tables Here is an example of inner join in SQL between two tables. Sample table: foods Sample table: company To join item name, item unit columns from foods table and company name, company city columns from company table, with the following condition - 1. company_id of foods and company table must be same, the following SQL statement can be used : SQL Code: SELECT foods.item_name,foods.item_unit, company.company_name,company.company_city FROM foods INNER JOIN company ON foods.company_id =company.company_id;Output: ITEM_NAME ITEM_ COMPANY_NAME COMPANY_CITY ------------------------- ----- ------------------------- -------------- Chex Mix Pcs Akas Foods Delhi Cheez-It Pcs Jack Hill Ltd London BN Biscuit Pcs Jack Hill Ltd London Mighty Munch Pcs Foodies. London Pot Rice Pcs Jack Hill Ltd London Jaffa Cakes Pcs Order All BostonExample of SQL INNER JOIN using JOIN keyword To get item name, item unit columns from foods table and company name, company city columns from company table, after joining these mentioned tables, with the following condition - 1. company id of foods and company id of company table must be same, the following SQL statement can be used: SQL Code: SELECT foods.item_name,foods.item_unit, company.company_name,company.company_city FROM foods JOIN company ON foods.company_id =company.company_id;Output: ITEM_NAME ITEM_ COMPANY_NAME COMPANY_CITY ------------------------- ----- ------------------------- ------------- Chex Mix Pcs Akas Foods Delhi Cheez-It Pcs Jack Hill Ltd London BN Biscuit Pcs Jack Hill Ltd London Mighty Munch Pcs Foodies. London Pot Rice Pcs Jack Hill Ltd London Jaffa Cakes Pcs Order All BostonPictorial Presentation of SQL Inner Join of Company and Foods Tables: SQL INNER JOIN for all columnsTo get all the columns from foods and company table after joining, with the following condition - 1. company id of foods and company id of company table must be same, the following SQL statement can be used: SQL Code: SELECT * FROM foods JOIN company ON foods.company_id =company.company_id;Output: ITEM_ID ITEM_NAME ITEM_ COMPAN COMPAN COMPANY_NAME COMPANY_CITY -------- ------------------------- ----- ------ ------ ------------------------- ------------- 1 Chex Mix Pcs 16 16 Akas Foods Delhi 6 Cheez-It Pcs 15 15 Jack Hill Ltd London 2 BN Biscuit Pcs 15 15 Jack Hill Ltd London 3 Mighty Munch Pcs 17 17 Foodies. London 4 Pot Rice Pcs 15 15 Jack Hill Ltd London 5 Jaffa Cakes Pcs 18 18 Order All BostonDifference between JOIN and INNER JOINJOIN 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. An SQL INNER JOIN is same as JOIN clause, combining rows from two or more tables. An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagram intersection. Inner joins use a comparison operator to match rows from two tables based on the values in common columns from each table. For example, retrieving all rows where the student identification number is the same for both the students and courses tables. Using JOIN Clause SELECT * FROM Table1 JOIN Table2 ON Table1.column_name=Table2.column_name;Using INNER JOIN Clause Difference between INNER JOIN and OUTER JOINAn INNER JOIN is such type of join that returns all rows from both the participating tables where the key record of one table is equal to the key records of another table. This type of join required a comparison operator to match rows from the participating tables based on a common field or column of both the tables. Where as the OUTER JOIN returns all rows from the participating tables which satisfy the condition and also those rows which do not match the condition will appear in this operation. This result set can appear in three types of format - The first one is LEFT OUTER JOIN, in this join includes all the rows from a left table of JOIN clause and the unmatched rows from a right table with NULL values for selected columns. The second one is RIGHT OUTER JOIN, in this join includes all rows from the right of JOIN cause and the unmatched rows from the left table with NULL values for selected columns. The last one in FULL OUTER JOIN, in this join, includes the matching rows from the left and right tables of JOIN clause and the unmatched rows from left and right table with NULL values for selected columns. Example: Here is two table tableX and tableY and they have no duplicate rows in each. In tableX the values ( A,B) are unique and in tableY the values (E,F) are unique, but the values (C and D) are common in both the tables. Here is INNER JOIN SELECT * FROM tableX INNER JOIN tableY on tableX.X = tableY.Y;or SELECT tableX.*,tableY.* FROM tableX,tableY WHERE tableX.X = tableY.Y;Output: Here only the matching of both tableX and tableY have appeared in the result set. Here is LEFT OUTER JOIN SELECT tableX.*,tableY.* FROM tableX,tableY WHERE tableX.X = tableY.Y(+)or SELECT * FROM tableX LEFT OUTER JOIN tableY ON tableX.X= tableY.YOutput: Here all the rows from tableX that is left side of JOIN clause and all the rows with NULL values for unmatched columns from tableY that is the right side of JOIN clause have appeared. Here is RIGHT OUTER JOIN SELECT * FROM tableX RIGHT OUTER JOIN tableY ON tableX.X= tableY.YOutput: Here all the rows from tableY that is the right side of JOIN clause and all the rows with NULL values for unmatched columns from tableX that is left side of JOIN clause have appeared. Here is FULL OUTER JOIN SELECT * FROM tableX FULL OUTER JOIN tableY ON tableX.X= tableY.YOutput: Here all the matching rows from tableX and tableY and all the unmatched rows with NULL values for both the tables have appeared. INNER JOIN ON vs WHERE clauseThe WHERE clause, what is done is that all records that match the WHERE condition are included in the result set but an INNER JOIN is that, data not matching the JOIN condition is excluded from the result set. Linking between two or more tables should be done using an INNER JOIN ON clause but filtering on individual data elements should be done with WHERE clause. INNER JOIN is ANSI syntax whereas the WHERE syntax is more relational model oriented. The INNER JOIN is generally considered more readable and it is a cartesian product of the tables, especially when you join lots of tables but the result of two tables JOIN'ed can be filtered on matching columns using the WHERE clause. INNER JOINS: Relational Databases
Key points to remember Click on the following to get the slides presentation - Outputs of the said SQL statement shown here is taken by using Oracle Database 10g Express Edition. Practice SQL Exercises
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JOIN Which type of join returns rows from two table only if there is a match between column in both table?Outer joins are joins that return matched values and unmatched values from either or both tables. There are a few types of outer joins: LEFT JOIN returns only unmatched rows from the left table, as well as matched rows in both tables.
Which join returns all the rows from table 2 and only those rows which match with that of table 1?What is Full Outer Join in SQL? In SQL the FULL OUTER JOIN combines the results of both left and right outer joins and returns all (matched or unmatched) rows from the tables on both sides of the join clause. Let's combine the same two tables using a full join.
Which join returns rows when there is a match in both tables?INNER JOIN TABLE2
When the Join condition is met, it returns matched rows in both tables with the selected columns in the SELECT clause.
Which type of join is used to returns all rows if there is one match in both tables * Inner join outer join full join left join?SQL outer join
On joining tables with a SQL inner join, the output returns only matching rows from both the tables.
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