SQL Server插入（如果不存在）

SQL Server Insert if not exist

我想在表中插入数据，但只插入数据库中不存在的数据！

这是我的代码：

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ALTER PROCEDURE [dbo].[EmailsRecebidosInsert]
(@_DE nvarchar(50),
@_ASSUNTO nvarchar(50),
@_DATA nvarchar(30) )
AS
BEGIN
INSERT INTO EmailsRecebidos (De, Assunto, DATA)
VALUES (@_DE, @_ASSUNTO, @_DATA)
WHERE NOT EXISTS ( SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND DATA = @_DATA);
END

错误是：

Msg 156, Level 15, State 1, Procedure EmailsRecebidosInsert, Line 11
Incorrect syntax near the keyword 'WHERE'.

号

相关讨论

而不是低于代码

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BEGIN
INSERT INTO EmailsRecebidos (De, Assunto, DATA)
VALUES (@_DE, @_ASSUNTO, @_DATA)
WHERE NOT EXISTS ( SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND DATA = @_DATA);
END

号

替换为

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BEGIN
IF NOT EXISTS (SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND DATA = @_DATA)
BEGIN
INSERT INTO EmailsRecebidos (De, Assunto, DATA)
VALUES (@_DE, @_ASSUNTO, @_DATA)
END
END

更新：(感谢@marc durdin指点)

请注意，在高负载下，这有时仍然会失败，因为在第一个连接执行插入之前，第二个连接可以通过if not exists测试，即竞争条件。请参阅stackoverflow.com/a/3791506/1836776，了解为什么即使在事务中包装也不能解决这个问题。

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对于那些寻找最快方法的人，我最近遇到了这些基准，其中显然使用了"insert select…"除了选择…"结果是5000万条或更多记录中最快的。

以下是本文中的一些示例代码(第三块代码最快)：

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INSERT INTO #table1 (Id, guidd, TimeAdded, ExtraData)
SELECT Id, guidd, TimeAdded, ExtraData
FROM #table2
WHERE NOT EXISTS (SELECT Id, guidd FROM #table1 WHERE #table1.id = #table2.id)
-----------------------------------
MERGE #table1 AS [Target]
USING (SELECT Id, guidd, TimeAdded, ExtraData FROM #table2) AS [SOURCE]
(id, guidd, TimeAdded, ExtraData)
ON [Target].id =[SOURCE].id
WHEN NOT MATCHED THEN
INSERT (id, guidd, TimeAdded, ExtraData)
VALUES ([SOURCE].id, [SOURCE].guidd, [SOURCE].TimeAdded, [SOURCE].ExtraData);
------------------------------
INSERT INTO #table1 (id, guidd, TimeAdded, ExtraData)
SELECT id, guidd, TimeAdded, ExtraData FROM #table2
EXCEPT
SELECT id, guidd, TimeAdded, ExtraData FROM #table1
------------------------------
INSERT INTO #table1 (id, guidd, TimeAdded, ExtraData)
SELECT #table2.id, #table2.guidd, #table2.TimeAdded, #table2.ExtraData
FROM #table2
LEFT JOIN #table1 ON #table1.id = #table2.id
WHERE #table1.id IS NULL

。

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我将使用合并：

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CREATE PROCEDURE [dbo].[EmailsRecebidosInsert]
(@_DE nvarchar(50),
@_ASSUNTO nvarchar(50),
@_DATA nvarchar(30) )
AS
BEGIN
WITH DATA AS (SELECT @_DE AS de, @_ASSUNTO AS assunto, @_DATA AS DATA)
MERGE EmailsRecebidos t
USING DATA s
ON s.de = t.de
AND s.assunte = t.assunto
AND s.data = t.data
WHEN NOT matched BY target
THEN INSERT (de, assunto, DATA) VALUES (s.de, s.assunto, s.data);
END

。

尝试以下代码

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ALTER PROCEDURE [dbo].[EmailsRecebidosInsert]
(@_DE nvarchar(50),
@_ASSUNTO nvarchar(50),
@_DATA nvarchar(30) )
AS
BEGIN
INSERT INTO EmailsRecebidos (De, Assunto, DATA)
SELECT @_DE, @_ASSUNTO, @_DATA
EXCEPT
SELECT De, Assunto, DATA FROM EmailsRecebidos
END

。

INSERT命令没有WHERE子句-您必须这样写：

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ALTER PROCEDURE [dbo].[EmailsRecebidosInsert]
(@_DE nvarchar(50),
@_ASSUNTO nvarchar(50),
@_DATA nvarchar(30) )
AS
BEGIN
IF NOT EXISTS (SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND DATA = @_DATA)
BEGIN
INSERT INTO EmailsRecebidos (De, Assunto, DATA)
VALUES (@_DE, @_ASSUNTO, @_DATA)
END
END

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我对SQL Server 2012也做了同样的事情，它起到了作用。

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INSERT INTO #table1 WITH (ROWLOCK) (Id, studentId, name)
SELECT '18769', '2', 'Alex'
WHERE NOT EXISTS (SELECT * FROM #table1 WHERE Id = '18769' AND studentId = '2')

相关讨论

取决于您的版本(2012年？)对于SQL Server，除了if exists之外，还可以使用merge，如下所示：

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ALTER PROCEDURE [dbo].[EmailsRecebidosInsert]
( @_DE nvarchar(50)
, @_ASSUNTO nvarchar(50)
, @_DATA nvarchar(30))
AS BEGIN
MERGE [dbo].[EmailsRecebidos] [Target]
USING (VALUES (@_DE, @_ASSUNTO, @_DATA)) [SOURCE]([De], [Assunto], [DATA])
ON [Target].[De] = [SOURCE].[De] AND [Target].[Assunto] = [SOURCE].[Assunto] AND [Target].[DATA] = [SOURCE].[DATA]
WHEN NOT MATCHED THEN
INSERT ([De], [Assunto], [DATA])
VALUES ([SOURCE].[De], [SOURCE].[Assunto], [SOURCE].[DATA]);
END

如下面的代码所述：执行下面的查询并验证您自己(它们是自解释的)

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CREATE TABLE `table_name` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`name` VARCHAR(255) NOT NULL,
`address` VARCHAR(255) NOT NULL,
`tele` VARCHAR(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB;

插入记录：

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INSERT INTO TABLE_NAME (name, address, tele)
SELECT * FROM (SELECT 'Nazir', 'Kolkata', '033') AS tmp
WHERE NOT EXISTS (
SELECT name FROM TABLE_NAME WHERE name = 'Nazir'
) LIMIT 1;
Query OK, 1 ROW affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0

SELECT * FROM `table_name`;

+----+--------+-----------+------+
| id | name | address | tele |
+----+--------+-----------+------+
| 1 | Nazir | Kolkata | 033 |
+----+--------+-----------+------+

。

现在，再次尝试插入相同的记录：

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INSERT INTO TABLE_NAME (name, address, tele)
SELECT * FROM (SELECT 'Nazir', 'Kolkata', '033') AS tmp
WHERE NOT EXISTS (
SELECT name FROM TABLE_NAME WHERE name = 'Nazir'
) LIMIT 1;

Query OK, 0 ROWS affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0

+----+--------+-----------+------+
| id | name | address | tele |
+----+--------+-----------+------+
| 1 | Nazir | Kolkata | 033 |
+----+--------+-----------+------+

号

插入其他记录：

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INSERT INTO TABLE_NAME (name, address, tele)
SELECT * FROM (SELECT 'Santosh', 'Kestopur', '044') AS tmp
WHERE NOT EXISTS (
SELECT name FROM TABLE_NAME WHERE name = 'Santosh'
) LIMIT 1;

Query OK, 1 ROW affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0

SELECT * FROM `table_name`;

+----+--------+-----------+------+
| id | name | address | tele |
+----+--------+-----------+------+
| 1 | Nazir | Kolkata | 033 |
| 2 | Santosh| Kestopur | 044 |
+----+--------+-----------+------+

号

相关讨论

你可以使用go命令。这将在出错后重新启动SQL语句的执行。在我的例子中，我有一些1000个insert语句，其中一些记录已经存在于数据库中，我只是不知道哪些记录。我发现，在处理了几百个之后，执行只会停止，并显示一条错误消息，因为记录已经存在，所以无法插入。挺烦人的，不过一走了之就解决了这个问题。这可能不是最快的解决方案，但速度不是我的问题。

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GO
INSERT INTO mytable (C1,C2,C3) VALUES(1,2,3)
GO
INSERT INTO mytable (C1,C2,C3) VALUES(4,5,6)
etc ...

。