SQLServer中交叉联接的用法介绍

select * from t1 cross join t2

select * from t1 cross join t2;--常用写法
select * from t1, t2;-- SQL:1989的规范
select * from t1 cross join t2
where t1.col1=t2.col2;--等价于内部联接
select * from t1 inner join t2  on t1.col1=t2.col2

-- 员工表
CREATE TABLE [dbo].[EmpInfo](
  [empId] [int] IDENTITY(1,1) NOT NULL,
  [empNo] [varchar](20) NULL,
  [empName] [nvarchar](20) NULL,
 CONSTRAINT [PK_EmpInfo] PRIMARY KEY CLUSTERED 
(
  [empId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF
, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

-- 奖金表
CREATE TABLE [dbo].[SalaryInfo](
  [id] [int] IDENTITY(1,1) NOT NULL,
  [empId] [int] NULL,
  [salary] [decimal](18, 2) NULL,
  [seasons] [varchar](20) NULL,
 CONSTRAINT [PK_SalaryInfo] PRIMARY KEY CLUSTERED 
(
  [id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF
, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
-- 季度表
CREATE TABLE [dbo].[Seasons](
  [name] [nchar](10) NULL
) ON [PRIMARY]

GO
SET IDENTITY_INSERT [dbo].[EmpInfo] ON 

INSERT [dbo].[EmpInfo] ([empId], [empNo], [empName]) VALUES (1, N'A001', N'王强')
INSERT [dbo].[EmpInfo] ([empId], [empNo], [empName]) VALUES (2, N'A002', N'李明')
INSERT [dbo].[EmpInfo] ([empId], [empNo], [empName]) VALUES (3, N'A003', N'张三')

INSERT [dbo].[SalaryInfo] ([id], [empId], [salary], [seasons])
 VALUES (1, 1, CAST(3000.00 AS Decimal(18, 2)), N'第一季度')
INSERT [dbo].[SalaryInfo] ([id], [empId], [salary], [seasons])
 VALUES (2, 3, CAST(5000.00 AS Decimal(18, 2)), N'第一季度')
INSERT [dbo].[SalaryInfo] ([id], [empId], [salary], [seasons])
 VALUES (3, 1, CAST(3500.00 AS Decimal(18, 2)), N'第二季度')
INSERT [dbo].[SalaryInfo] ([id], [empId], [salary], [seasons])
 VALUES (4, 3, CAST(3000.00 AS Decimal(18, 2)), N'第二季度 ')
INSERT [dbo].[SalaryInfo] ([id], [empId], [salary], [seasons])
 VALUES (5, 2, CAST(4500.00 AS Decimal(18, 2)), N'第二季度')

INSERT [dbo].[Seasons] ([name]) VALUES (N'第一季度')
INSERT [dbo].[Seasons] ([name]) VALUES (N'第二季度')
INSERT [dbo].[Seasons] ([name]) VALUES (N'第三季度')
INSERT [dbo].[Seasons] ([name]) VALUES (N'第四季度')

-- 查询每个人每个季度的奖金情况 如果奖金不存在则为0
SELECT a.empName,b.name seasons ,isnull(c.salary,0) salary 
FROM EmpInfo a 
CROSS JOIN Seasons b
LEFT OUTER JOIN SalaryInfo c ON a.empId=c.empId AND b.name=c.seasons