[英]How to select column names from multiple tables in SQL server 2008 by avoiding certain columns which reoccur in all tables
I have a database that stores the complete details of the employees of a firm. 我有一个数据库,存储公司员工的完整详细信息。 I need to select column names from multiple tables in the database which when executed would provide me the columns required to list specific details.
我需要从数据库中的多个表中选择列名,这些表在执行时会为我提供列出特定详细信息所需的列。 So, I tried the following query which returns the columns of the specified table only.
所以,我尝试了以下查询,该查询仅返回指定表的列。
SELECT TABLE_NAME,COLUMN_NAME
FROM mydatabase.INFORMATION_SCHEMA.COLUMNS Where TABLE_NAME=N'TBLemppersonaldetails'
All the tables have a Column named 'EmployeeId' which can be considered as a primary key. 所有表都有一个名为“EmployeeId”的列,可以将其视为主键。 Now, how could i get all required columns from all the tables by avoiding certain columns such as Update Date,Mode that repeats in all the tables.
现在,我怎么能通过避免某些列来获取所有表中的所有必需列,例如更新日期,模式在所有表中重复。 I would prefer using 'Inner Join' to join all the tables.
我更喜欢使用'Inner Join'加入所有表格。 For example consider the tables below:
例如,考虑下表:
Table1 Table2
EmployeeId Name Address Mode EmployeeId Gender BloodGroup Mode
---------------------------------------- -------------------------------------------
001 abc No.9,vv 1 001 Male O+ve 1
street,
Considering the example above, I require the columns EmployeeId,Name,Address,Gender,BloodGroup to be listed after the execution of the query while excluding the column named 'Mode' from both the tables. 考虑到上面的示例,我要求在执行查询后列出EmployeeId,Name,Address,Gender,BloodGroup列,同时从两个表中排除名为“Mode”的列。 I request you to consider another scenario where the so called 'PrimaryKey' constraint doesn't exist for the 'EmployeeId' Column.
我请求您考虑另一种情况,即'EmployeeId'列中不存在所谓的'PrimaryKey'约束。 PS: I am using SQL Server 2008
PS:我正在使用SQL Server 2008
Try this one - 试试这个 -
DDL: DDL:
SET NOCOUNT ON;
IF OBJECT_ID (N'dbo.Table1') IS NOT NULL
DROP TABLE dbo.Table1
CREATE TABLE dbo.Table1
(
EmployeeId INT
, Name VARCHAR(30)
, [Address] VARCHAR(150)
, Mode INT
, Img IMAGE
, UpdateDate DATETIME
, IpAddress VARCHAR(20)
)
IF OBJECT_ID (N'dbo.Table2') IS NOT NULL
DROP TABLE dbo.Table2
CREATE TABLE dbo.Table2
(
EmployeeId INT
, Gender VARCHAR(6)
, BloodGroup VARCHAR(20)
, Mode INT
)
INSERT INTO dbo.Table1 (EmployeeId, Name, [Address], Mode, UpdateDate, IpAddress)
VALUES ('001', 'abc', 'No.9,vv street', 1,'06/04/2013 12:00:00','192.168.0.1')
INSERT INTO dbo.Table2 (EmployeeId, Gender, BloodGroup, Mode)
VALUES ('001', 'Male', 'O+ve', 1)
Query: 查询:
DECLARE @SQL NVARCHAR(MAX)
;WITH cte AS
(
SELECT
column_name = '[' + c.name + ']'
, table_name = '[' + s.name + '].[' + o.name + ']'
, [type_name] = t.name
FROM sys.columns c WITH (NOLOCK)
JOIN sys.objects o WITH (NOLOCK) ON c.[object_id] = o.[object_id]
JOIN sys.schemas s WITH (NOLOCK) ON o.[schema_id] = s.[schema_id]
JOIN sys.types t WITH (NOLOCK) ON c.user_type_id = t.user_type_id
WHERE o.name IN ('Table1', 'Table2')
AND s.name = 'dbo'
AND o.[type] = 'U'
AND c.name NOT IN ('Mode', 'UpdateDate', 'IpAddress')
), unicol AS (
SELECT TOP 1 column_name
FROM cte
GROUP BY cte.column_name
HAVING COUNT(cte.column_name) > 1
), cols AS
(
SELECT DISTINCT column_name, [type_name]
FROM cte
), tbl AS
(
SELECT DISTINCT table_name
FROM cte
), rs AS
(
SELECT
tbl.table_name
, column_name = ISNULL(cte.column_name, cols.column_name + ' = NULL')
FROM cols
CROSS JOIN tbl
LEFT JOIN cte ON cols.column_name = cte.column_name AND cte.table_name = tbl.table_name
), rs2 AS (
SELECT uni = ' UNION ALL' + CHAR(13) + 'SELECT ' + STUFF((
SELECT ', ' + rs.column_name
FROM rs
WHERE tbl.table_name = rs.table_name
GROUP BY rs.column_name
ORDER BY rs.column_name
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, '') +
' FROM ' + table_name
FROM tbl
)
SELECT @SQL = 'SELECT
' + STUFF((
SELECT CHAR(13) + ', ' + ISNULL(unicol.column_name, cols.column_name + ' = MAX('
+ CASE
WHEN [type_name] = 'image' THEN 'CONVERT(VARBINARY(MAX), ' + cols.column_name + ')'
WHEN [type_name] = 'bit' THEN 'CAST(' + cols.column_name + ' AS CHAR(1))'
ELSE cols.column_name
END + ')')
FROM cols
LEFT JOIN unicol ON cols.column_name = unicol.column_name
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 2, ' ')
+ '
FROM
(' + STUFF((
SELECT CHAR(10) + uni
FROM rs2
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 11, '') + CHAR(13) +
') t
GROUP BY ' + (SELECT column_name FROM unicol)
PRINT @SQL
EXECUTE sys.sp_executesql @SQL
Output: 输出:
Address BloodGroup EmployeeId Gender Img Name
------------------ ------------ ----------- ------ -------- -------
No.9,vv street O+ve 1 Male NULL abc
You need to dynamically create a SQL statement and then run that command 您需要动态创建SQL语句,然后运行该命令
Update 22.06.2013 更新于2013年6月22日
IF OBJECT_ID('dbo.Table1') IS NOT NULL DROP TABLE dbo.Table1
CREATE TABLE dbo.Table1
(
EmployeeId int PRIMARY KEY,
Name varchar(100),
Address varchar(100),
Mode int
)
INSERT dbo.Table1
VALUES(1, 'abc', 'Address', 1)
IF OBJECT_ID('dbo.Table2') IS NOT NULL DROP TABLE dbo.Table2
CREATE TABLE dbo.Table2
(
EmployeeId int PRIMARY KEY,
Gender varchar(100),
BloodGroup varchar(100),
Mode int
)
INSERT dbo.Table2
VALUES(1, 'Male', 'O+ve', 1)
DECLARE @TablesWithAlias TABLE([schema] varchar(10), name varchar(20), alias varchar(10))
INSERT @TablesWithAlias
VALUES('dbo', 'Table1', 't1.'),
('dbo', 'Table2', 't2.')
DECLARE @dsql nvarchar(max)
SELECT @dsql = COALESCE(@dsql + ',', '') + MIN(twa.alias) + CASE WHEN o.IsPrimaryKey IS NOT NULL THEN c.name ELSE c.name END
FROM sys.schemas s
JOIN sys.tables t ON s.schema_id = t.schema_id
JOIN sys.columns c ON t.object_id = c.object_id
OUTER APPLY (
SELECT CASE WHEN OBJECTPROPERTY(object_id(constraint_name), 'IsPrimaryKey') = 1 THEN 1 END AS IsPrimaryKey
FROM information_schema.key_column_usage k
WHERE s.name = k.table_schema AND t.name = k.table_name
AND c.name = k.COLUMN_NAME
) o
JOIN @TablesWithAlias twa ON s.name = twa.[schema] AND t.name = twa.name
GROUP BY c.column_id, c.name, o.IsPrimaryKey
HAVING COUNT(*) = 1 OR o.IsPrimaryKey IS NOT NULL
ORDER BY c.column_id
PRINT @dsql
--Your 'Inner Join' to join all the tables.
SET @dsql =
'SELECT ' + @dsql +
' FROM dbo.Table1 t1 JOIN dbo.Table2 t2 ON t1.EmployeeId = t2.EmployeeId '
PRINT @dsql
EXEC sp_executesql @dsql
Search your column name using this : 使用以下方法搜索列名称:
SELECT OBJECT_NAME (object_id ),*
FROM sys.columns
WHERE name LIKE 'ColumnName'
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