Displaying Histogram-Horizontal
===========================
- select deptno,lpad('*',count(*),'*') as cnt from emp group by deptno
Histogram-Vertical
===============
- select row_number( )over(partition by deptno order by empno) rn,
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case when deptno=10 then '*' else null end deptno_10,
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case when deptno=20 then '*' else null end deptno_20,
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case when deptno=30 then '*' else null end deptno_30
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from emp
Displaying only the histogram
============================
- select max(deptno_10) d10,
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max(deptno_20) d20,
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max(deptno_30) d30
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from (
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select row_number( )over(partition by deptno order by empno) rn,
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case when deptno=10 then '*' else null end deptno_10,
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case when deptno=20 then '*' else null end deptno_20,
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case when deptno=30 then '*' else null end deptno_30
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from emp
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) x
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group by rn
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order by 1 desc, 2 desc, 3 desc
