在 MS SQL Server 中删除表

-- 说明:
-- 1. 要删除表 table_name, 须先判断该表是否正被数据库中其它表所引用.
-- 2. 如果未被引用, 可直接 DROP TABLE table_name; 否则必须先删除引用表的约束, 再 DROP TABLE table_name.
-- 3. 另外, table_name 是否正引用其它表的情况无须考虑.


-- 创建主表
CREATE TABLE tParent
(
tParent_Col1 int NOT NULL CONSTRAINT pkParent PRIMARY KEY,
tParent_Col2 nvarchar(50) NOT NULL CONSTRAINT uktParent UNIQUE
)

INSERT INTO tParent VALUES (1, N'ParentRecord1')
INSERT INTO tParent VALUES (2, N'ParentRecord2')
INSERT INTO tParent VALUES (3, N'ParentRecord3')
SELECT * from tParent
-- ===========================================

-- 创建从表 1
CREATE TABLE tChild1
(
tChild1_Col1 int NOT NULL CONSTRAINT fkChild1Parent FOREIGN KEY REFERENCES tParent (tParent_Col1),
tChild1_Col2 nvarchar(50) NOT NULL
)

INSERT INTO tChild1 VALUES (2, N'Child1Record1')
INSERT INTO tChild1 VALUES (3, N'Child1Record2')
INSERT INTO tChild1 VALUES (1, N'Child1Record3')
INSERT INTO tChild1 VALUES (2, N'Child1Record4')
SELECT * from tChild1
-- ===========================================

-- 创建从表 2
CREATE TABLE tChild2
(
tChild2_Col1 int NOT NULL,
tChild2_Col2 nvarchar(50) NOT NULL CONSTRAINT fkChild2Parent FOREIGN KEY REFERENCES tParent (tParent_Col2)
)

INSERT INTO tChild2 VALUES (11, N'ParentRecord2')
INSERT INTO tChild2 VALUES (22, N'ParentRecord1')
INSERT INTO tChild2 VALUES (33, N'ParentRecord3')
INSERT INTO tChild2 VALUES (44, N'ParentRecord3')
SELECT * from tChild2
-- ===========================================

-- 生成删除从表外键约束的 T-SQL 语句
-- 1. MS SQL Server 2000
DECLARE @stmt nvarchar(4000)
SELECT @stmt = ISNULL(@stmt + CHAR(13) + CHAR(10), '')
+ 'ALTER TABLE ' + OBJECT_NAME(fkeyid)
+ ' DROP CONSTRAINT ' + OBJECT_NAME(constid)
from sysforeignkeys
WHERE rkeyid = OBJECT_ID(N'tParent', N'U')

-- --