Logical operators are used in the SELECT statement to retrieve records based on one or more conditions. While querying data in sql programming, programmer can combine more than one logical operator to apply multiple search conditions. As same as in comparison operator, the conditions specified by the logical operators are connected with the WHERE clause.
The syntax for using the logical operators in the SELECT
SELECT column_list
FROM table_name
WHERE conditional_expression 1 logical operator Conditional_expression 2
Where
Basically there are three types of logical operators in every computer programming. They are Or, And & Not, described below with example.
OR: Return a true value when at least one condition is satisfied. The following SQL query retrieves records from the Department table when the GroupName is either Manufacturing or Quality Assurance:
SELECT * FROM HumanResources.Department WHERE GroupName = 'Manufacturing' OR GroupName = 'Quality Assurance'
AND: Is used to join two conditions and returns a true value when both the conditions are satisfied. For example, to view the details of all the employees of Adventure Works who are married and working as an Engineering Manager, you can use the AND logical operator, as shown in the following SQL query:
SELECT * FROM HumanResources.Employee WHERE Title = 'Engineering Manager' AND MaritalStatus = 'M'
NOT: Reverses the result of the search condition. The following SQL query retrieves records from the Department table when the GroupName is not Manufacturing or Quality Assurance:
SELECT * FROM Humansources.Employee WHERE Title = 'Design Engineer' And NOT MaritalStatus = 'F'
The preceding query retrieves all the rows, except the rows that match the condition specified after the NOT conditional expression.
The syntax for using the logical operators in the SELECT
SELECT column_list
FROM table_name
WHERE conditional_expression 1 logical operator Conditional_expression 2
Where
- column_list: list of fields to be shown in output.
- table_name: from the records are to be retrieved.
- conditional_expression 1 and conditional_expression 2 are any conditional expressions.
- logical operator: any operator listed below.
Basically there are three types of logical operators in every computer programming. They are Or, And & Not, described below with example.
OR: Return a true value when at least one condition is satisfied. The following SQL query retrieves records from the Department table when the GroupName is either Manufacturing or Quality Assurance:
SELECT * FROM HumanResources.Department WHERE GroupName = 'Manufacturing' OR GroupName = 'Quality Assurance'
AND: Is used to join two conditions and returns a true value when both the conditions are satisfied. For example, to view the details of all the employees of Adventure Works who are married and working as an Engineering Manager, you can use the AND logical operator, as shown in the following SQL query:
SELECT * FROM HumanResources.Employee WHERE Title = 'Engineering Manager' AND MaritalStatus = 'M'
NOT: Reverses the result of the search condition. The following SQL query retrieves records from the Department table when the GroupName is not Manufacturing or Quality Assurance:
SELECT * FROM Humansources.Employee WHERE Title = 'Design Engineer' And NOT MaritalStatus = 'F'
The preceding query retrieves all the rows, except the rows that match the condition specified after the NOT conditional expression.
Tidak ada komentar:
Posting Komentar