Shulou(Shulou.com)06/01 Report--

# case: query the salary level of an employee

SELECT salary,grade_levelFROM employees eJOIN job_grades gON e.`salary`BETWEEN g.`lowest _ sal`AND g.`lowest _ sal`

# case: query the number of each salary grade and descend by rank

SELECT COUNT (*), grade_levelFROM job_grades jJOIN employees eON e.`salary`BETWEEN j.`lowest _ sal`and j.`highest _ sal`GROUP BY grade_level DESC

Content extension:

Grammar

Select query list

From Table 1 alias [connection Type]

Jion Table 2 Alias

On connection condition

[where filter criteria]

[group by grouping]

[having filter criteria]

[order by sorted list]

Case 1: query employee name, department name

SELECT last_name,department_nameFROM employees eINNER JOIN departments dON e.department_id=d.department_id

Case 2: query employee name and job name with e in the name (add filter)

SELECT last_name,job_titleFROM employees eINNER JOIN jobs jON e.job_id=j.job_idWHERE e.last_name LIKE'% e%'

The above is all the knowledge points of this introduction.

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