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    id         name
    1            a
    2            b
    3            c
    4            c
    5            b
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select distinct name from table
µÃµ½µÄ½á¹ûÊÇ:
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name
    a
    b
    c
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select distinct name, id from table
½á¹û»áÊÇ:
----------
id name
    1 a
    2 b
    3 c
    4 c
    5 b
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select id, distinct name from table
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select *, count(distinct name) from table group by name
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    id name count(distinct name)
    1 a 1
    2 b 1
    3 c 1
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