SQL LEFT JOIN clause is used to select all the matched records from the left side table, regardless if it has matched records in the right side table or not.

SQL LEFT JOIN Clause Syntax

SELECT Table1.Column1, Table1.Column2, ... , Table2.Column1, Table2.Column2, ...
FROM Table1
ON Table1.ColumnName = Table2.ColumnName

SQL LEFT JOIN Clause Example

Table: Employees

EmployeeId FirstName LastName Department Salary
203 Mazojys Fxoj Finance 78000
204 Jozzh Lnanyo Finance 45800
205 Syllauu Dfaafk Finance 57000
206 Gecrrcc Srlkrt Finance 62000

Table: Tickets

TicketID TicketNo EmployeeId
1 2349 203
2 2400 204
3 2438 205

Select all the employees, if they have any tickets, list the tickets:

SELECT Employees.EmployeeId
           , Employees.FirstName
           , Employees.LastName
           , Tickets.TicketNo
FROM Employees
ON Employees.EmployeeId = Tickets.EmployeeId

The result will look like:

EmployeeId FirstName LastName TicketNo
203 Mazojys Fxoj 2349
204 Jozzh Lnanyo 2400
205 Syllauu Dfaafk 2438
206 Gecrrcc Srlkrt

Note: The employee whose EmployeeId is 206 doesn’t have any records matched in the table Tickets, but he is still listed in the result with the TicketNo null.

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