SQL Server 2005及以后版本：

IF EXISTS(SELECT 1 FROM sys.columns 
          WHERE Name = N'columnName'
          AND Object_ID = Object_ID(N'schemaName.tableName'))
BEGIN
    -- Column Exists
END

马丁·史密斯的版本更短：

IF COL_LENGTH('schemaName.tableName', 'columnName') IS NOT NULL
BEGIN
    -- Column Exists
END

if exists (
  select * 
  from INFORMATION_SCHEMA.COLUMNS 
  where TABLE_NAME = '<table_name>' 
  and COLUMN_NAME = '<column_name>'
) begin
  print 'Column you have specified exists'
end else begin
  print 'Column does not exist'
end

SQL Server 2005及以后版本：

IF EXISTS(SELECT 1 FROM sys.columns 
          WHERE Name = N'columnName'
          AND Object_ID = Object_ID(N'schemaName.tableName'))
BEGIN
    -- Column Exists
END

马丁·史密斯的版本更短：

IF COL_LENGTH('schemaName.tableName', 'columnName') IS NOT NULL
BEGIN
    -- Column Exists
END

以下查询可用于检查表中是否存在搜索列。我们可以根据搜索结果做出决定，如下所示。

IF EXISTS (SELECT 'Y' FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = <YourTableName> AND COLUMN_NAME = <YourColumnName>)
  BEGIN
    SELECT 'Column Already Exists.'
  END
  ELSE
  BEGIN
    ALTER TABLE <YourTableName> ADD <YourColumnName> <DataType>[Size]
  END

declare @myColumn   as nvarchar(128)
set @myColumn = 'myColumn'
if not exists (
    select  1
    from    information_schema.columns columns 
    where   columns.table_catalog   = 'myDatabase'
        and columns.table_schema    = 'mySchema' 
        and columns.table_name      = 'myTable' 
        and columns.column_name     = @myColumn
    )
begin
    exec('alter table myDatabase.mySchema.myTable add'
    +'    ['+@myColumn+'] bigint       null')
end

接受答案的临时表格版本：

if (exists(select 1
           from tempdb.sys.columns
           where Name = 'columnName'
                 and Object_ID = object_id('tempdb..#tableName')))
begin
...
end