获取列类型的SQL语句

Question

是否有可以返回表中列类型的SQL语句？

Answer 1

使用SQL Server:

SELECT DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS
WHERE 
     TABLE_NAME = 'yourTableName' AND 
     COLUMN_NAME = 'yourColumnName'

Answer 2

TSQL中最简单的方法是:

SELECT COLUMN_NAME, DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'yourTableName'

Answer 3

对于SQL Server,此系统存储过程将返回所有表信息,包括列数据类型:

exec sp_help YOURTABLENAME

Answer 4

在TSQL/MSSQL中,它看起来像:

SELECT t.name, c.name 
FROM sys.tables t 
JOIN sys.columns c ON t.object_id = c.object_id
JOIN sys.types y ON y.user_type_id = c.user_type_id
WHERE t.name = ''

Answer 5

在oracle SQL中你会这样做:

SELECT
    DATA_TYPE
FROM
    all_tab_columns 
WHERE
    table_name = 'TABLE NAME' -- in uppercase
AND column_name = 'COLUMN NAME' -- in uppercase

Answer 6

如果你使用MySQL,你可以试试

SHOW COLUMNS FROM `tbl_name`;

在dev.mysql.com上显示列

否则你应该可以做到

DESCRIBE `tbl_name`;

Answer 7

为了建立在上面的答案的基础上，以声明列所需的相同格式获取列数据类型通常很有用。

例如，varchar(50)、varchar(max)、decimal(p, s)。

这允许您这样做：

SELECT 
  [Name]         = c.[name]
, [Type]         = 
    CASE 
      WHEN tp.[name] IN ('varchar', 'char') THEN tp.[name] + '(' + IIF(c.max_length = -1, 'max', CAST(c.max_length AS VARCHAR(25))) + ')' 
      WHEN tp.[name] IN ('nvarchar','nchar') THEN tp.[name] + '(' + IIF(c.max_length = -1, 'max', CAST(c.max_length / 2 AS VARCHAR(25)))+ ')'      
      WHEN tp.[name] IN ('decimal', 'numeric') THEN tp.[name] + '(' + CAST(c.[precision] AS VARCHAR(25)) + ', ' + CAST(c.[scale] AS VARCHAR(25)) + ')'
      WHEN tp.[name] IN ('datetime2') THEN tp.[name] + '(' + CAST(c.[scale] AS VARCHAR(25)) + ')'
      ELSE tp.[name]
    END
, [RawType]      = tp.[name]
, [MaxLength]    = c.max_length
, [Precision]    = c.[precision]
, [Scale]        = c.scale
FROM sys.tables t 
JOIN sys.schemas s ON t.schema_id = s.schema_id
JOIN sys.columns c ON t.object_id = c.object_id
JOIN sys.types tp ON c.user_type_id = tp.user_type_id
WHERE s.[name] = 'dbo' AND t.[name] = 'MyTable'

Answer 8

这也有效，因为它仅选择列名称及其各自的字符类型

SELECT COLUMN_NAME ,DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'Items';   

Answer 9

使用 TSQL/MSSQL

此查询将获得：表名、列名、数据类型、数据类型长度和允许的空值

SELECT TABLE_NAME,COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, IS_NULLABLE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'your_table_name'

唯一需要更改的是your_table_name。

Answer 10

要检索实际声明的数据类型，例如在动态 SQL 中用于 ALTER COLUMN，可以使用类似以下内容：

SELECT
    TABLE_NAME, 
    COLUMN_NAME,
    DATA_TYPE
        + CASE WHEN DATA_TYPE IN ('char','nchar','varchar','nvarchar','binary','varbinary')
                    AND CHARACTER_MAXIMUM_LENGTH > 0 THEN
                 COALESCE('('+CONVERT(varchar,CHARACTER_MAXIMUM_LENGTH)+')','')
            ELSE '' END
        + CASE WHEN DATA_TYPE IN ('decimal','numeric') THEN
                COALESCE('('+CONVERT(varchar,NUMERIC_PRECISION)+','+CONVERT(varchar,NUMERIC_SCALE)+')','')
            ELSE '' END
        AS Declaration_Type,
    CASE WHEN IS_NULLABLE='NO' THEN 'NOT ' ELSE '' END + 'NULL' AS Nullable
FROM INFORMATION_SCHEMA.COLUMNS
ORDER BY 1,2

Answer 11

使用MS SQL的另一个变体:

SELECT TYPE_NAME(system_type_id) 
FROM sys.columns 
WHERE name = 'column_name'
AND [object_id] = OBJECT_ID('[dbo].[table_name]');

Answer 12

从 SQL Server 2012 开始：

SELECT * FROM sys.dm_exec_describe_first_result_set( N'SELECT * FROM [my].[Table]', NULL, 0 );

Answer 13

只要有人觉得这有用。在 SQL Server 中：

sp_columns 'yourtablename'

这将提供所有列的详细信息。它为您提供列名称、数据类型、类型名称、精度、长度、iss_nullable 等。