Question

我想创建一个SQL命令来创建一个带条件的索引。索引所基于的列以及过滤器表达式中使用的列都可能不存在所以我添加了一个条件，两列都存在，但我仍然得到过滤器表达式中列的无效列名称错误。有办法解决这个问题吗？

IF EXISTS (SELECT 1 
       FROM sys.all_columns 
       WHERE name='Field1' 
       AND object_id=OBJECT_ID('[dbo].[Table1]') )
AND EXISTS (SELECT 1 
       FROM sys.all_columns 
       WHERE name='Field2' 
       AND object_id=OBJECT_ID('[dbo].[Table1]') )

BEGIN

CREATE NONCLUSTERED INDEX [IX_Table1_Field1] ON [dbo].[Table1]
(
    [Field1]
) 
WHERE ([Field2]=(1))

END

出现问题的表

CREATE TABLE [dbo].[Table1] (
     [Field1] [int] 
)

Answer 1

如果我理解你真正想要的东西，我认为你需要像这样使用动态SQL：

declare @tableName nvarchar(max) = N'Table2', @field1 nvarchar(max) = N'Field1', @field2 nvarchar(max) = N'Field2';
declare @sql nvarchar(max) = '';

if exists (select 1 
       from sys.all_columns
       where name = @field1
       and [object_id] = object_id(@tableName))
and exists (select 1 
       from sys.all_columns
       where name = @field2
       and [object_id] = object_id(@tableName))
begin
    set @sql = 'create nonclustered index [IX_'+@tableName+'_'+@field1+'] on [dbo].['+@tableName+'] ( ['+@field1+']) where ['+@field2+']= 1';
end
else if exists (select 1 
       from sys.all_columns
       where name = @field1
       and [object_id] = object_id(@tableName))
begin
    set @sql = 'create nonclustered index [IX_'+@tableName+'_'+@field1+'] on [dbo].['+@tableName+'] ( ['+@field1+'])';
end
else if exists (select 1 
       from sys.all_columns
       where name = @field2
       and [object_id] = object_id(@tableName))
begin
    set @sql = 'create nonclustered index [IX_'+@tableName+'_'+@field2+'] on [dbo].['+@tableName+'] ( ['+@field2+'])';
end

exec sp_sqlexec @sql;
go

当筛选表达式中的列可能不存在时，SQL筛选索引？

1 个答案: