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2025-04-01 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Database >
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An example of sql for fetching the first piece of data is as follows:
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SELECT * FROM tableName where fd_rt ='A'--and rownum=1 ORDER BY fd_date DESC
Normally, the first piece of data should be 16bf4eb91606de5e0ff61f94d0f8f20f
The result of using this sql directly with the condition after where is as follows
SELECT * FROM tableName where fd_rt ='A'
And rownum=1
ORDER BY fd_date DESC
But the query result is the second piece of data.
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The correct way to use it is:
SELECT t.* from (SELECT * FROM tableName where fd_rt ='A' ORDER BY fd_date DESC) t WHERE rownum = 1
The query result of rownum as a pseudo column is actually:
SELECT tableName. *, rownum FROM tableName where fd_rt ='A'--and rownum=1 ORDER BY fd_date DESC
SELECT t.charting Rownum from (SELECT * FROM tableName where fd_rt ='A' ORDER BY fd_date DESC) t
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