Question

我想借助其他表的外键更新一个表。

我正在尝试做这样的事情：

UPDATE tbl_1 
SET field1 = 6, field12 = NULL 
WHERE field3 = (SELECT tbl_2.item1 
                FROM tbl_1, tbl_2 
                WHERE tbl_1.field3 = tbl_2.item1 AND tbl_2.item2 = 135)

OR

UPDATE tbl_1 
SET field1 = 6, field12 = NULL 
WHERE field3 = (SELECT item1 FROM tbl_2 WHERE item2 = 135)

Answer 1

我认为以下任何一种都可行：

UPDATE  tbl_1 
SET     field1 = 6, field12 = NULL 
WHERE   EXISTS 
        (   SELECT 1
            FROM tbl_2 
            WHERE tbl_1.field3 = tbl_2.item1 
            AND tbl_2.item2 = 135
        )

或

UPDATE tbl_1 SET field1 = 6, field12 = NULL WHERE field3 IN (SELECT item1 FROM tbl_2 WHERE item2 = 135)

Answer 2

这是因为SELECT返回多行。这样做：

UPDATE tbl_1 SET field1 = 6, field12 = NULL 
WHERE field3 IN (SELECT item1 FROM tbl_2 WHERE item2 = 135)

当SELECT返回一个表（或多行）时，使用IN。如果您确定内部查询应该只返回一行，那么您必须相应地调整内部查询。像这样左右：

UPDATE tbl_1 SET field1 = 6, field12 = NULL 
WHERE field3 = (SELECT item1 FROM tbl_2 WHERE item2 = 135 ORDER BY myValue LIMIT 1)

在这里使用IN更安全'因为它可以处理从SELECT语句返回的单个记录和多个记录。

Answer 3

您还可以使用INSERT OR REPLACE语句，如下所示：

假设tbl_1有4列：key，field1，field2，field3
并且您希望使用tbl_2

中的匹配值更新field2

INSERT OR REPLACE INTO tbl_1
SELECT tbl_1.key, tbl_1.field1, tbl_2.value, tbl_1.field3
FROM tbl_1 JOIN tbl_2 ON tbl_2.key = tbl_1.key

Answer 4

单值：

UPDATE tbl_1 
SET field1 = 6, field12 = NULL 
WHERE field3 = (SELECT tbl_2.item1 
                FROM tbl_1, tbl_2 
                WHERE tbl_1.field3 = tbl_2.item1 AND tbl_2.item2 = 135)

对于多个值

UPDATE tbl_1 
SET field1 = 6, field12 = NULL 
WHERE field3 IN (SELECT tbl_2.item1 
                FROM tbl_1, tbl_2 
                WHERE tbl_1.field3 = tbl_2.item1 AND tbl_2.item2 = 135)

Answer 5

你可以像这样使用

UPDATE tbl_1 
SET field1 = 6, field12 = NULL 
WHERE field3 in (SELECT tbl_2.item1 
                FROM tbl_1, tbl_2 
                WHERE tbl_1.field3 = tbl_2.item1 AND tbl_2.item2 = 135)

sqlite不支持加入更新查询。所以这是选项之一

如何在SQLite中使用select语句更新表

5 个答案: