数据库去重的sql语句

以下是常用的数据库去重的 SQL 语句示例：

MySQL:

1. 通过 DISTINCT 去重

SELECT DISTINCT column1, column2, ...
FROM table_name;

2. 通过 GROUP BY 去重

SELECT column1, column2, ...
FROM table_name
GROUP BY column1, column2, ...;

3. 通过子查询去重

SELECT column1, column2, ...
FROM table_name
WHERE column_name IN (
  SELECT DISTINCT column_name
  FROM table_name
);

Oracle:

1. 通过 DISTINCT 去重

SELECT DISTINCT column1, column2, ...
FROM table_name;

2. 通过 GROUP BY 去重

SELECT column1, column2, ...
FROM table_name
GROUP BY column1, column2, ...;

3. 通过 ROW_NUMBER() 去重

SELECT column1, column2, ...
FROM (
  SELECT column1, column2, ..., ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY column_name) rn
  FROM table_name
)
WHERE rn = 1;

SQL Server:

1. 通过 DISTINCT 去重

SELECT DISTINCT column1, column2, ...
FROM table_name;

2. 通过 GROUP BY 去重

SELECT column1, column2, ...
FROM table_name
GROUP BY column1, column2, ...;

3. 通过 ROW_NUMBER() 去重

SELECT column1, column2, ...
FROM (
  SELECT column1, column2, ..., ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY column_name) rn
  FROM table_name
)
WHERE rn = 1;

注意：以上示例仅供参考，具体的语法和实现可能会因数据库类型、版本和数据结构而有所不同。