Concept explainers
SELECT statement:
It is used to retrieve information from the table or
SELECT * FROM table_Name;
WHERE clause:
“WHERE” statement is used limit the number of rows. For example: Consider a table “FTable” that has two columns named “FruitName” and “Color”. “WHERE” clause is used when there is a need to display the entire FruitName whose color is Red.
SELECT * FROM FTable WHERE color = 'red';
When the above statement is executed, red colored fruits get displayed.
Aggregate Functions:
SQL has some built-in functions and they are called as aggregate functions. SQL contains five built-in functions. They are:
- SUM – This function is used to add values from the particular column.
- Syntax: SELECT SUM(column_Name) FROM table_Name;
- COUNT – This is used to count the number of rows for the particular column.
- Syntax: SELECT COUNT(column_Name) FROM table_Name;
- MAX – This function is used to get the maximum value from the column.
- Syntax: SELECT MAX(column_Name) FROM table_Name;
- MIN – This function is used to get the minimum value from the column.
- Syntax: SELECT MIN(column_Name) FROM table_Name;
- AVG – This function is used to get the average of all the values from the column.
- Syntax: SELECT AVG(column_Name) FROM table_Name;
Join:
Join is a relational operation, which combines the data from two or more tables into single table or view, then that is called as Join.
Inner join:
The “inner join” keyword is to select the matching records from two tables. The syntax of “inner join” is as follows:
Syntax:
SELECT column_name FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name;
“AND” operator:
The operator used to check two or more conditions using single query. The “AND” operator returns “true” when two conditions are satisfied in the query.
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Database Systems: Design, Implementation, & Management
- Database Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781285196145Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos CoronelPublisher:Cengage LearningDatabase Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781305627482Author:Carlos Coronel, Steven MorrisPublisher:Cengage Learning