我想向表中插入数据，但只插入数据库中不存在的数据。
这是我的代码:
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，级别15，状态1，程序EmailsRecebidosInsert，第11行 关键字WHERE附近的语法不正确。
当前回答
如果你想检查一个键是否存在，你可以使用:
INSERT INTO tableName (...) VALUES (...)
ON DUPLICATE KEY
UPDATE ...
使用这个，如果已经有一个特定键的条目，那么它将更新，否则，它将插入。
其他回答
INSERT命令没有WHERE子句——你必须这样写:
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
只需将代码更改为使用SELECT而不是VALUES
INSERT INTO EmailsRecebidos (De, Assunto, Data)
SELECT @_DE, @_ASSUNTO, @_DATA
WHERE NOT EXISTS (SELECT * FROM EmailsRecebidos
WHERE De = @_DE
AND Assunto = @_ASSUNTO
AND Data = @_DATA);
如下面的代码所解释:执行以下查询并自行验证。
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;
插入一个记录:
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，尝试再次插入相同的记录:
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 |
+----+--------+-----------+------+
插入一条不同的记录:
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 |
+----+--------+-----------+------+
您可以使用GO命令。这将在错误发生后重新启动SQL语句的执行。在我的情况下，我有一些1000 INSERT语句，其中一些记录已经存在于数据库中，我只是不知道是哪一个。 我发现在处理了几个100之后，执行就会停止，并出现一个错误消息，它不能插入，因为记录已经存在。很烦人，但按GO键解决了这个问题。这可能不是最快的解决方案，但速度不是我的问题。
GO
INSERT INTO mytable (C1,C2,C3) VALUES(1,2,3)
GO
INSERT INTO mytable (C1,C2,C3) VALUES(4,5,6)
etc ...
试试下面的代码
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
