在要建立索引的表的列中找到重复的值,可以通过以下步骤进行:
SELECT column_name, COUNT(*)
FROM table_name
GROUP BY column_name
HAVING COUNT(*) > 1;
这将返回重复值及其出现次数。
SELECT column_name
FROM table_name
WHERE column_name IN (
SELECT column_name
FROM table_name
GROUP BY column_name
HAVING COUNT(*) > 1
);
这将返回重复的值。
SELECT column_name
FROM (
SELECT column_name, ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY column_name) AS row_num
FROM table_name
) AS subquery
WHERE row_num > 1;
这将返回重复的值。
以上是几种常见的方法来在要建立索引的表的列中找到重复的值。根据具体情况选择合适的方法。
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