Query processing and data analysis
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The document discusses different types of joins in SQL including inner joins, natural joins, non-equijoins, outer joins, self joins, and cross joins. It provides the syntax and examples for each type of join. Joins combine data from two or more tables by using common columns, usually primary keys and foreign keys.
![*Property of STI K0019
Types of Joins
Equijoins or Inner Joins
The equijoin or inner join combines two tables with a
common column which is usually the primary key.
Syntax:
SELECT TABLE1.COLUMN1, TABLE2.COLUMN2...
FROM TABLE1, TABLE2 [, TABLE3 ]
WHERE TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME
[ AND TABLE1.COLUMN_NAME = TABLE3.COLUMN_NAME ]](https://image.slidesharecdn.com/queryprocessinganddataanalysis-150817175424-lva1-app6891/85/Query-processing-and-data-analysis-3-320.jpg)
![*Property of STI K0019
Types of Joins
Natural Joins
The natural join removes duplicate columns in the joining
columns.
Syntax:
SELECT TABLE1.*, TABLE2.COLUMN_NAME
[ TABLE3.COLUMN_NAME ]
FROM TABLE1, TABLE2 [ TABLE3 ]
WHERE TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME
[ AND TABLE1.COLUMN_NAME = TABLE3.COLUMN_NAME ]](https://image.slidesharecdn.com/queryprocessinganddataanalysis-150817175424-lva1-app6891/85/Query-processing-and-data-analysis-5-320.jpg)
![*Property of STI K0019
Types of Joins
Non-equijoins
It combines two or more tables based on a specified column
value not equaling a specified column value in another table.
Syntax:
SELECT TABLE1.*, TABLE2.COLUMN_NAME
[ TABLE3.COLUMN_NAME ]
FROM TABLE1, TABLE2 [, TABLE3 ]
WHERE TABLE1.COLUMN_NAME != TABLE2.COLUMN_NAME
[ AND TABLE1.COLUMN_NAME != TABLE2.COLUMN_NAME ]](https://image.slidesharecdn.com/queryprocessinganddataanalysis-150817175424-lva1-app6891/85/Query-processing-and-data-analysis-7-320.jpg)
![*Property of STI K0019
Types of Joins
Outer Joins (cont.)
Syntax:
SELECT TABLE1.COLUMN_NAME, TABLE2.COLUMN_NAME
FROM TABLE1
{RIGHT | LEFT | FULL} [OUTER] JOIN
TABLE2 ON TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME
Example:
SELECT EMPLOYEE_TBL.EMP_ID, SALARY_TBL.DATE_HIRE
FROM EMPLOYEE_TBL LEFT OUTER JOIN
SALARY_TBL ON EMPLOYEE_TBL.EMP_ID = SALARY_TBL.EMP_ID;](https://image.slidesharecdn.com/queryprocessinganddataanalysis-150817175424-lva1-app6891/85/Query-processing-and-data-analysis-10-320.jpg)
![*Property of STI K0019
Types of Joins
Self Joins
The self join combines tables to itself.
Syntax:
SELECT A.COLUMN_NAME, B.COLUMN_NAME,
[ C.COLUMN_NAME ]
FROM TABLE1 A, TABLE2 B [, TABLE3 C ]
WHERE A.COLUMN_NAME = B.COLUMN_NAME
[ AND A.COLUMN_NAME = C.COLUMN_NAME ]](https://image.slidesharecdn.com/queryprocessinganddataanalysis-150817175424-lva1-app6891/85/Query-processing-and-data-analysis-11-320.jpg)
Query processing and data analysis
- 1. *Property of STI K0019 Retrieving Data from Several Tables What is a Join? Types of Join
- 2. *Property of STI K0019 What is a Join? A join is a collection of data from multiple tables. It combines two or more tables to retrieve data from multiple tables. The primary keys and foreign keys are used to join related tables to one another.
- 3. *Property of STI K0019 Types of Joins Equijoins or Inner Joins The equijoin or inner join combines two tables with a common column which is usually the primary key. Syntax: SELECT TABLE1.COLUMN1, TABLE2.COLUMN2... FROM TABLE1, TABLE2 [, TABLE3 ] WHERE TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME [ AND TABLE1.COLUMN_NAME = TABLE3.COLUMN_NAME ]
- 4. *Property of STI K0019 Types of Joins Equijoins or Inner Joins (cont.) Example: SELECT DISTINCT name, size, order_items.quantity FROM product, order_items WHERE product.id = order_items.prod_id AND product.quantity = order_items.quantity
- 5. *Property of STI K0019 Types of Joins Natural Joins The natural join removes duplicate columns in the joining columns. Syntax: SELECT TABLE1.*, TABLE2.COLUMN_NAME [ TABLE3.COLUMN_NAME ] FROM TABLE1, TABLE2 [ TABLE3 ] WHERE TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME [ AND TABLE1.COLUMN_NAME = TABLE3.COLUMN_NAME ]
- 6. *Property of STI K0019 Types of Joins Natural Joins (cont.) Example: SELECT product.*, order_items.quantity FROM product, order_items WHERE product.id = order_items.prod_id
- 7. *Property of STI K0019 Types of Joins Non-equijoins It combines two or more tables based on a specified column value not equaling a specified column value in another table. Syntax: SELECT TABLE1.*, TABLE2.COLUMN_NAME [ TABLE3.COLUMN_NAME ] FROM TABLE1, TABLE2 [, TABLE3 ] WHERE TABLE1.COLUMN_NAME != TABLE2.COLUMN_NAME [ AND TABLE1.COLUMN_NAME != TABLE2.COLUMN_NAME ]
- 8. *Property of STI K0019 Types of Joins Non-equijoins (cont.) Example: SELECT EMPLOYEE_TBL.EMP_ID, SALARY_TBL.DATE_HIRE FROM EMPLOYEE_TBL, SALARY_TBL WHERE EMPLOYEE_TBL.EMP_ID != SALARY_TBL.EMP_ID;
- 9. *Property of STI K0019 Types of Joins Outer Joins It produces all rows that exist in one table, even if there are corresponding rows do not exist in the joined table. The left outer join preserves every row in the left-hand table. The right outer join preserves every row in the right-hand table. A full outer join, preserves all rows from both tables.
- 10. *Property of STI K0019 Types of Joins Outer Joins (cont.) Syntax: SELECT TABLE1.COLUMN_NAME, TABLE2.COLUMN_NAME FROM TABLE1 {RIGHT | LEFT | FULL} [OUTER] JOIN TABLE2 ON TABLE1.COLUMN_NAME = TABLE2.COLUMN_NAME Example: SELECT EMPLOYEE_TBL.EMP_ID, SALARY_TBL.DATE_HIRE FROM EMPLOYEE_TBL LEFT OUTER JOIN SALARY_TBL ON EMPLOYEE_TBL.EMP_ID = SALARY_TBL.EMP_ID;
- 11. *Property of STI K0019 Types of Joins Self Joins The self join combines tables to itself. Syntax: SELECT A.COLUMN_NAME, B.COLUMN_NAME, [ C.COLUMN_NAME ] FROM TABLE1 A, TABLE2 B [, TABLE3 C ] WHERE A.COLUMN_NAME = B.COLUMN_NAME [ AND A.COLUMN_NAME = C.COLUMN_NAME ]
- 12. *Property of STI K0019 Types of Joins Self Joins (cont.) Example: SELECT A.LAST_NAME, B.LAST_NAME, A.FIRST_NAME FROM EMPLOYEE_TBL A, EMPLOYEE_TBL B WHERE A.LAST_NAME = B.LAST_NAME;
- 13. *Property of STI K0019 Types of Joins Cross Joins It returns all possible combinations of rows from the two tables. Syntax: SELECT * FROM TABLE1 CROSS JOIN TABLE2 Example: SELECT * FROM ORDER CROSS JOIN PURCHASE