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SQL MIN() and MAX() functions
- min() returns the smallest value and max() functions is viceversa.
Example
SELECT MIN(price) FROM payroll
SQL COUNT(), AVG() and SUM() function
- Count() returns the number of rows that matches a specified column. ❗NULL values are not counted
- AVG() returns the average value of a numeric column. ❗NULL values are ignored.
- Sum() returns the total of a numeric column.❗NULL values are ignored.
SQL LIKE operator
- LIKE operator is used in a WHERE condition to search a specified form in a column.
- wildcards that are often used in conjunction with the LIKE operator:
- percent sign (%)represents zero, one, or multiple characters
- underscore sign(_) represents one, a single character
SQL Wildcards
- This is used to search data within a table.
- it is often used with the LIKE operator and this operator is used in a WHERE clause to search for a specified pattern in a column.
| symbol | Description | Example |
| * | Represents zero or more characters | fo% fin finds fool, font |
| - | Represents a single character | h_t finds hot, hut, hat and hit |
| [] | any single letter within the brackets | h[oat] find hot and hat but not hit |
| ^ | any letter not in the bracket | h[^oa]t finds hit but not hot and hat |
| - | any single character in the specified range | c[a-b]t finds cat and cbt |
SQL IN
- this operator tests whether a specified value matches any value.
- IN operator is shorthand for multiple OR conditions.
Example
SELECT * FROM table_name WHERE column IN('value1', 'value2', 'value3');
SQL BETWEEN
- this operator selects values within a given range and it can be number text or dates
Example
#this will display price 200 to 1000 of the table
SELECT * FROM payroll WHERE price BETWEEN 200 AND 1000
SQL ALIASES
- This is used to give a table or column a temporary name and often used to make column names more readable.
- An Aliases only exists for the duraton of that query.
Example
SELECT CustomerNames AS Names FROM Customers