SQLSERVER--Exec的用法

USE DB;  
GO   
--Create The Table. We'll pull info from here for our dynamic SQL  
CREATE TABLE DynamicSQLExample  (
  TableID int IDENTITY NOT NULL  CONSTRAINT PKDynamicSQLExample  PRIMARY KEY,
  SchemaName varchar(128) NOT NULL,
  TableName varchar(128) NOT NULL
); 
GO   
/* Populate the table. In this case, We're grabbing every user  ** table object in this database */  
INSERT INTO DynamicSQLExample  
SELECT s.name AS SchemaName, t.name AS TableName  
FROM sys.schemas s  JOIN sys.tables t  
ON s.schema_id = t.schema_id;
GO 



DECLARE @SchemaName varchar(128)
DECLARE @TableName varchar(128)
-- Now, grab the table name that goes with our ID  
SELECT @SchemaName = SchemaName, @TableName = TableName  
FROM DynamicSQLExample  
WHERE TableID = 3  
-- Finally, pass that value into the EXEC statement  
EXEC ('SELECT * FROM ' + @SchemaName + '.' + @TableName)