How can you update fields across tables in SQL Server?

To update a field across tables in SQL Server, you can use an inner join subquery, a self-join, or the MERGE statement.

Option 1: Method 1 involves using an inline subquery.

UPDATE 表1
SET 字段 = (SELECT 字段 FROM 表2 WHERE 条件)
WHERE 条件;

Option 1: Method 2: Utilizing self-connection.

UPDATE 表1
SET 字段 = 表2.字段
FROM 表1
INNER JOIN 表2 ON 表1.条件 = 表2.条件;

Option 3: Utilize the MERGE statement.

MERGE INTO 表1
USING 表2
ON 条件
WHEN MATCHED THEN
    UPDATE SET 表1.字段 = 表2.字段;

In the three mentioned methods, it is necessary to set appropriate conditions based on the actual situation to ensure the accuracy of cross-table updates.