SQL subqueries on employee Database: Find the number of employees are performing the duty of a manager

Last update on May 30 2022 07:16:25 (UTC/GMT +8 hours)

SQL subqueries on employee Database: Exercise-76 with Solution

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76. From the following table, write a SQL query to count the number of employees who work as a manager. Return number of employees.

Sample table: employees

Sample Solution:

SELECT count(*)
FROM employees
WHERE emp_id IN
    (SELECT manager_id
     FROM employees);

SELECT count(DISTINCT m.emp_id)
FROM employees w,
     employees m
WHERE w.manager_id = m.emp_id ;

Sample Output:

 count
-------
     6
(1 row)

Relational Algebra Expression:

Relational Algebra Tree:

Structure of employee Database:

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Previous: From the following table, write a SQL query to find the maximum average salary drawn for each job except for PRESIDENT.
Next: From the following table, write a SQL query to find those departments where no employee works. Return department ID.

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SQL Server SELECT into existing table.

INSERT INTO dbo.TABLETWO
SELECT col1, col2
  FROM dbo.TABLEONE
 WHERE col3 LIKE @search_key

This assumes there's only two columns in dbo.TABLETWO - you need to specify the columns otherwise:

INSERT INTO dbo.TABLETWO
  (col1, col2)
SELECT col1, col2
  FROM dbo.TABLEONE
 WHERE col3 LIKE @search_key

Database: SQL Server

Ref: https://bit.ly/3y6tpA3