如果不存在带有参数值的DB2插入行 [英] DB2 insert row if not exist with value from parameter

问题描述

我想在表中插入一行（如果尚不存在）。我有以下直接执行的代码：

I want to insert a row into a table if it doesn't exists yet. I have following code that executes directly:

insert into MyTable (Column1, Column2, Year, Code, Id, UPDATE_IDENT)
select 'Default', 'Default', 2014, '', 0, 0
from sysibm.sysdummy1
WHERE NOT EXISTS (SELECT * FROM MyTable 
WHERE Column1 = 'c1'
AND Column2 = 'c2'
AND Year = 2014)

但是当我按年份将其更改为参数化方法：

However when i change this to a paramtered method by year:

insert into MyTable (Column1, Column2, Year, Code, Id, UPDATE_IDENT)
select 'Default', 'Default', @year, '', 0, 0
from sysibm.sysdummy1
WHERE NOT EXISTS (SELECT * FROM MyTable 
WHERE Column1 = 'c1'
AND Column2 = 'c2'
AND Year = @year)

还尝试了在原子部分中使用声明的变量，但没有成功：

Also tried with a declared variable in an atomic part with no success:

BEGIN ATOMIC
DECLARE varJaar INTEGER;
SET varYear = @year;
insert into MyTable (Column1, Column2, Year, Code, Id, UPDATE_IDENT)
select 'Default', 'Default', varYear , '', 0, 0
from sysibm.sysdummy1
WHERE NOT EXISTS (SELECT * FROM MyTable 
WHERE Column1 = 'c1'
AND Column2 = 'c2'
AND Year = varYear )
END;

我无法执行此操作，因为无法在我的选择部分中使用参数。试图将@year修改为@year作为Year，但是仍然没有成功。

I cannot execute this because i cannot use a parameter in my select part. Tried to modify @year to @year as Year, but still no success.

有没有一种方法可以声明temp变量或在我的选择中使用此参数的东西

Is there a way i can declare a temp variable or something to use this parameter in my select part?

推荐答案

最终通过创建临时表解决了此问题。
变量被临时存储。该表应自动清除，但是在触发我的方法之前，我仍然在try-catch块中执行drop table命令：

Solved this eventually by creating a temp table. The variable is stored temporarily. This table should be cleared automatically however i still perform a drop table command in a try-catch block before triggering my method:

Try
    Dim adapter As New DataAdapter()
    Dim commandText As String = "drop table QTEMP.tempVariable"
    Dim command As DbCommand = adapter.CreateDbCommand(commandText)

    adapter.ExecuteNonQuery(command)

 Catch notHandledEx As Exception
 End Try

 create table #tempVariable (year int);
 insert into #tempVariable values(@Year);

 insert into MyTable (Column1, Column2, Year, Code, Id, UPDATE_IDENT)
 select 'Default', 'Default',  (select max(year) from #tempVariable), '', 0, 0
 from sysibm.sysdummy1
 WHERE NOT EXISTS (SELECT * FROM MyTable 
 WHERE Column1 = 'c1'
 AND Column2 = 'c2'
 AND Year = @Year)

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