- What is the difference between SQL and MySQL?
- What do you mean by DBMS? What are its different types?
- What are the types of joins in SQL? Give an example for each one.
- What is a Primary key?
- What are the different operators available in SQL?
- What is the need for group functions in SQL?
- What is a Relationship and what are they?
Please discuss these questions with your partners and post your answers as a comment on this gist when you are finished.
Room 6 :
Mohamad Sheikh Alshabab, Najwan, Farah, Lunar
0- SQL is a query programming language that manages RDBMS. MySQL is a relational database management system that uses SQL.
1- DBMS: A database management system (DBMS) is system software for creating and managing databases. A DBMS makes it possible for end users to create, protect, read, update and delete data in a database, It handles tasks like data storage, retrieval, and management.
Types of DBMS:
It also has a hierarchical structure, but the data is organized like a graph and it is allowed to have more than one parent for one child record.
2-
Returns matching rows from both tables.
Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column;
Returns all rows from the left table and matching rows from the right table.
Example: SELECT * FROM table1 LEFT JOIN table2 ON table1.column = table2.column;
Returns all rows from the right table and matching rows from the left table.
Example: SELECT * FROM table1 RIGHT JOIN table2 ON table1.column = table2.column;
Returns all rows when there is a match in either table.
Example: SELECT * FROM table1 FULL JOIN table2 ON table1.column = table2.column;
Returns the Cartesian product of both tables.
Example: SELECT * FROM table1 CROSS JOIN table2;
Joins a table with itself using aliases.
Example: SELECT e1.name, e2.name FROM employees e1 INNER JOIN employees e2 ON e1.manager_id = e2.employee_id;
3- is a column in a relational database table that's distinctive for each record.
4- SQL Arithmetic Operators · SQL Bitwise Operators · SQL Comparison Operators · SQL Compound Operators · SQL Logical Operators
5- Group functions, also known as aggregate functions, are essential in SQL for performing calculations on sets of values and summarizing data in a result set. These functions operate on a group of rows and return a single value for each group. The need for group functions in SQL arises from several reasons:
Summarizing Data:
Group functions allow you to perform calculations on a set of values within a specific group. For example, you can calculate the total sales, average salary, or maximum value for each group.
Statistical Analysis:
SQL group functions provide statistical measures like average, standard deviation, variance, etc., which are useful for analyzing data distributions within groups.
Data Aggregation:
They help in aggregating data from multiple rows into a single result. This is particularly important when working with large datasets where summarizing information is necessary for meaningful analysis.
Reporting:
Group functions are commonly used in generating reports where aggregated data is presented. For instance, you might want to show the total sales for each product category or the average score for each student in a class.
Data Analysis and Business Intelligence:
In the context of data analysis and business intelligence, group functions play a crucial role in extracting meaningful insights from datasets. They enable users to analyze trends, patterns, and summarize key metrics.
Efficiency:
Group functions improve the efficiency of data retrieval and analysis by allowing you to perform calculations directly in the database engine. This reduces the amount of data transferred between the database and the application, leading to better performance.
Combining with GROUP BY Clause:
Group functions are typically used in conjunction with the GROUP BY clause, which divides the result set into groups based on one or more columns. This facilitates the aggregation of data within each group.
Flexibility in Analysis:
Group functions provide flexibility in the type of analysis you can perform, whether it's finding the minimum or maximum value, calculating the average, or counting the number of occurrences within each group.
Commonly used SQL group functions include:
COUNT(): Counts the number of rows in a group.
SUM(): Calculates the sum of values in a group.
AVG(): Calculates the average of values in a group.
MIN(): Finds the minimum value in a group.
MAX(): Finds the maximum value in a group.
In summary, group functions are indispensable in SQL for summarizing, analyzing, and extracting meaningful information from datasets, making them a fundamental aspect of database querying and reporting.
6- Relationships are the established associations between two or more tables. Relationships are based on common fields from more than one table, often involving primary and foreign keys.One-to-One (1:1),One-to-Many (1:N),Many-to-Many (M:N).