Tag Archives: database

Structured Query Language (SQL) – Understanding Table JOINS

Structured Query Language (SQL) – Understanding Table JOINS

1)      INNER JOIN

The inner join is given as

SELECT d.Dept_name, e.emp_name

FROM Department  d

INNER JOIN employee e

ON d.dept_id = e.dept_id

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Structured Query Language (SQL) – Using the UNION / UNION ALL

Structured Query Language (SQL) – Using the UNION / UNION ALL

In this case, let’s consider the tables such that it will be easier to understand the intricacies of the Union.

Table DEPARTMENT contains the Dept_ID and the Dept_name.

Table EMPLOYEE contains the Emp_ID, emp_name, incentives, deductions  and contains the details for the permanent employees.

Table TEMP_EMPLOYEE contains the EMP_ID, emp_name and contains the details for temporary employees. The tables have been segregated to understand the UNION query.

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