SQL OR vs AND
In SQL, the
AND operators are used to combine multiple conditions in the
WHERE clause of a query to filter and retrieve data from a database table. However, they have different logical behaviors:
WHERE department = 'Sales' OR salary > 50000;
This query retrieves all employees who are either in the “Sales” department or have a salary greater than $50,000.
ANDoperator returns true only if all the conditions it combines are true.It is used to narrow down the query results, retrieving rows that meet all of the specified conditions.When using
AND, all conditions must evaluate to true for the entire condition to be true.
WHERE order_date >= '2023-01-01' AND order_date <= '2023-12-31' AND total_amount > 1000;
This query retrieves orders placed in the year 2023 with a total amount greater than $1000. All three conditions must be met for a row to be included in the result.
Here’s a summary of the key differences:
ORbroadens the query results, while
ANDnarrows them down.
OR, at least one condition must be true for the entire expression to be true.
AND, all conditions must be true for the entire expression to be true.
You can also use parentheses to control the order of evaluation when combining
OR operators in more complex queries to ensure the desired logic is applied.