Question

我可以复制一行并在同一个表中更改单个字段的值，这样就完全正常了：

INSERT INTO myTable (foo,bar)
    SELECT foo,'new bar'
    FROM myTable
    WHERE rowIndex=5

但是我想用内联变量替换'new bar'。我试过这个无济于事：

DECLARE @Bar varchar(50) = 'new bar'
INSERT INTO myTable (foo,bar)
    SELECT foo,@Bar
    FROM myTable
    WHERE rowIndex=5

我刚刚抛出一个错误，指出@Bar是一个无效的列。

有办法做到这一点吗？

Answer 1

我在笔记本电脑上运行此代码 - SQL Server 2K8 v10.0.1600

CREATE TABLE #MyTable (
  rowIndex Int IDENTITY(1, 1),
  foo VarChar(10),
  bar VarChar(50)
);

DECLARE @Bar VarChar(50) = 'new bar';
INSERT INTO #MyTable (foo, bar)
    SELECT foo, @Bar
    FROM #MyTable
    WHERE rowIndex = 5;

DROP TABLE #MyTable;

如果作为单个批次执行它并且（与临时表除外）与您的相同，它可以正常工作。

Answer 2

万一你认为Yuck的答案在临时表中存在问题，这是一个非临时表

CREATE TABLE 
         myTable 
  (foo varchar (50),
   bar varchar(50) ,
   rowIndex int identity)

SET identity_INSERT MyTable on 
INSERT INTO myTable  (foo, bar, rowIndex ) values ('foo','bar', 50)
SET identity_INSERT MyTable oFF

DECLARE @Bar varchar(50) = 'new bar'
INSERT INTO myTable (foo,bar)
    SELECT foo,@Bar
    FROM myTable
    WHERE rowIndex=50

    select foo, bar , rowIndex
    from myTable
    Drop table mytable

结果

foo bar     rowIndex
--- ------- --------
foo bar     50
foo new bar 51

这也可以在c＃中使用SQLDataClient

using(SqlConnection cnn = new SqlConnection("Data Source=yoursever;Initial  Catalog=yourDB;Integrated Security=SSPI;"))
{ 
    cnn.Open();
    SqlCommand cmd = cnn.CreateCommand();

    cmd.CommandText = @"DECLARE @Bar varchar(50) = 'new bar' 
                        INSERT INTO myTable (foo,bar)   
                        SELECT foo,
                             @Bar    
                         FROM 
                           myTable    
                         WHERE rowIndex=50";
    cmd.ExecuteNonQuery();
}

Answer 3

而不是：

DECLARE @Bar VarChar(50) = 'new bar'

你能试试吗？：

DECLARE @Bar VarChar(50) 
SET @Bar = 'new bar'

Answer 4

你应该使用Stored Procedures

这样的东西

对不起，这可能是我的经历，但我以前从未见过插入SELECT？

MYSQL示例

DELIMITER //
    CREATE PROCEDURE InsertInto_myTable(
        IN Bar              VARCHAR(11)
    )
    BEGIN
        INSERT INTO `myTable` (foo,bar) SELECT `foo`,@Bar FROM `myTable` WHERE rowIndex = 5;
    END //
DELIMITER ;

完成此操作后，您只需致电CALL InsertInto_myTable('new bar')

MSSQL示例

CREATE PROCEDURE InsertInto_myTable(
    Bar varchar(50)
)
BEGIN
    INSERT INTO myTable (foo,bar) 
    SELECT foo,@Bar
    FROM myTable
    WHERE rowIndex=5;
END

使用 EXECUTE InsertInto_myTable('new bar');

SQL在SELECT中使用变量

4 个答案: