DISTINCT
关键字。,,``sql,SELECT DISTINCT column1, column2 FROM table_name;,
`,,这样会返回
column1 和
column2` 组合的唯一记录。DISTINCT
关键字去除重复数据。GROUP BY
和 HAVING
子句。,,``sql,SELECT column_name, COUNT(*),FROM table_name,GROUP BY column_name,HAVING COUNT(*) > 1;,
``,,这段代码会返回在指定列中出现次数超过一次的所有记录。sql,SELECT column_name, COUNT(*),FROM table_name,GROUP BY column_name,HAVING COUNT(*) > 1;,
`,,这条语句会返回
table_name 表中
column_name` 列值相同的所有记录的数量,并且只显示那些出现次数超过一次的记录。sql,SELECT column_name, COUNT(*),FROM table_name,GROUP BY column_name,HAVING COUNT(*) > 1;,
``,,这段代码会返回在指定列中出现次数超过一次的所有数据。Powered By Z-BlogPHP 1.7.3
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