我需要在SQL server上编写一个查询,以获得特定表中的列列表,其相关数据类型(长度)以及它们是否不为空。我已经做到了这么多。

但现在我还需要得到,在同一个表中,对一个列- TRUE,如果该列是一个主键。

我该怎么做呢?

我的期望输出是:

Column name | Data type | Length | isnull | Pk

当前回答

为了确保获得正确的长度,需要将unicode类型视为一种特殊情况。参见下面的代码。

更多信息请参见:https://msdn.microsoft.com/en-us/library/ms176106.aspx

SELECT 
   c.name 'Column Name',
   t.name,
   t.name +
   CASE WHEN t.name IN ('char', 'varchar','nchar','nvarchar') THEN '('+

             CASE WHEN c.max_length=-1 THEN 'MAX'

                  ELSE CONVERT(VARCHAR(4),

                               CASE WHEN t.name IN ('nchar','nvarchar')

                               THEN  c.max_length/2 ELSE c.max_length END )

                  END +')'

          WHEN t.name IN ('decimal','numeric')

                  THEN '('+ CONVERT(VARCHAR(4),c.precision)+','

                          + CONVERT(VARCHAR(4),c.Scale)+')'

                  ELSE '' END

   as "DDL name",
   c.max_length 'Max Length in Bytes',
   c.precision ,
   c.scale ,
   c.is_nullable,
   ISNULL(i.is_primary_key, 0) 'Primary Key'
FROM    
   sys.columns c
INNER JOIN 
   sys.types t ON c.user_type_id = t.user_type_id
LEFT OUTER JOIN 
   sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
LEFT OUTER JOIN 
   sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
WHERE
   c.object_id = OBJECT_ID('YourTableName')

其他回答

查找数据类型和长度的组合结果,并以“NULL”和“非空”的形式为空。

SELECT c.name AS 'Column Name',
       t.name + '(' + cast(c.max_length as varchar(50)) + ')' As 'DataType',
       case 
         WHEN  c.is_nullable = 0 then 'null' else 'not null'
         END AS 'Constraint'
  FROM sys.columns c
  JOIN sys.types t
    ON c.user_type_id = t.user_type_id
 WHERE c.object_id    = Object_id('TableName')

你会发现结果如下所示。

谢谢你!

在查询编辑器中选择表名并按Alt+F1,它将带来表的所有信息。

我有点惊讶居然没人提

sp_help 'mytable'
SELECT COLUMN_NAME, IS_NULLABLE, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH FROM information_schema.columns WHERE table_name = '<name_of_table_or_view>'

在上面的语句中运行SELECT *,以查看information_schema. schema是什么。列的回报。

这个问题之前已经回答过了- https://stackoverflow.com/a/11268456/6169225

Marc_s的答案很好,但如果主键列出现在其他索引中,这些列会出现不止一次,那么它就有一个缺陷。如。

演示:

create table dbo.DummyTable
(
    id int not null identity(0,1) primary key,
    Msg varchar(80) null
);

create index NC_DummyTable_id ON DummyTable(id);

下面是我用来解决这个问题的存储过程:

create or alter procedure dbo.GetTableColumns
(
    @schemaname nvarchar(128),
    @tablename nvarchar(128)
)
AS
BEGIN
    SET NOCOUNT ON;

    with ctePKCols as
    (
        select 
            i.object_id,
            ic.column_id
        from 
            sys.indexes i
            join sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
        where 
            i.is_primary_key = 1
    )
    SELECT
        c.name AS column_name,
        t.name AS typename,
        c.max_length AS MaxLength,
        c.precision,
        c.scale,
        c.is_nullable,
        is_primary_key = CASE WHEN ct.column_id IS NOT NULL THEN 1 ELSE 0 END
    FROM 
        sys.columns c
        JOIN sys.types t ON t.user_type_id = c.user_type_id
        LEFT JOIN ctePKCols ct ON ct.column_id = c.column_id AND ct.object_id = c.object_id
    WHERE 
        c.object_ID = OBJECT_ID(quotename(@schemaname) + '.' + quotename(@tablename))
    
END 
GO

exec dbo.GetTableColumns 'dbo', 'DummyTable'