![]() The syntax of this join is as follows: SELECT lumn_1, lumn_2. The missing values for the rows from the right table, in the result of the join, are represented by NULL values. Left Outer Join, also known as the Left Join, results in a table containing all the rows from the table on the left side of the join (the first table), and only the rows that satisfy the join condition, from the table on the right side of the join (the second table). The resulting table contains only the three rows with the same value for the column “EmployeeID”, in both the tables. This is what the final table would look like: If no condition is specified, this join behaves as a “Cross Join”.įor example, if you want to join the tables “Employee” and “Department” based on the “EmployeeID” column, you must use the following query: The most significant difference between the Inner join and the “Natural Join” is that the common columns appear more than once, whereas they appear only once in the result of Natural Join.The basic syntax of this join is: SELECT lumn_1, lumn_2…Īs you can see, the condition is specified after the “ON” statement. This join returns all the rows with matching values in both the tables. Only the rows that satisfy the join predicate are included in the result table. The query checks all the rows of table1 and table2. ![]() This condition is applied on the columns of both the tables on either side of the join clause. Using the Inner Join, the tables are combined on the basis of a condition, also known as the join predicate. If you want to join all the columns from both the tables, you can use the following syntax: SELECT * FROM table1, table2 įor example, if you want to Cross Join columns “EmployeeID”, “Name”, “Dept_Name”, and “Position” from our tables “Employee” and “Department”, use the following query:Īs you can see, the resulting table consists of 30 rows as our “Employee” and “Department” tables have 6 and 5 rows, respectively. The syntax of this join is as follows: SELECT lumn_1, lumn_2.lumn_1, lumn_2… ![]() For example, if table A contains 20 rows and table B consists of 30 rows, the Cross Join of these tables will result in a table will containing 20*30 (600) rows. Cartesian JoinĬartesian Join also known as the Cross Join, returns the cartesian product of the tables being joined, which is the combination of every row of one table with every row of another table. You must use the following query to join these two: SELECT * FROM EmployeeĪs you can see, the join was performed based on the common column “EmployeeID”, and the rows that had the same value for this column in both the tables, have been joined. If you want to perform a natural join on the entire table you can use the following syntax: SELECT * FROM table_1įor example, if there’s a table “Employee”:Īnd you want to Natural Join it with the following table “Department”: Natural join can be used to combine two or more tables, and the syntax of it is as follows: SELECT column_1, column_2.column_n The common columns only appear once in the result of this join. This join is used to combine rows of tables based on columns having the same name and data type in both the tables. Let’s get a more in-depth insight into all of these Joins in SQL. ![]() The result table contains all the rows from both the tables Self Join ![]() The result table contains all the rows from the second table Full Outer Join The result table contains all the rows from the first table Right Outer Join The result table consists of only the common rows Left Outer Join Returns the cartesian product of tables’ rows Inner Join Used to join tables on the basis of a common column Cartesian Join ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |