如何将这两个SQL语句组合成一个,并与MSSQL2000和2005兼容?

sys.foreign_keys 在SQL Server 2005中引入。你得用 sysobjects 与SQL Server 2000和2005兼容。

试试这个SQL:

IF NOT EXISTS (
    SELECT NULL FROM sysobjects 
    WHERE name = 'FK_myTableName_otherTable' 
    AND parent_obj = OBJECT_ID(N'myTableName'))
ALTER TABLE myTableName
WITH CHECK 
ADD CONSTRAINT [FK_myTableName_otherTable] 
FOREIGN KEY([columnName]) 
REFERENCES otherTable ([otherColumn])

if not exists (SELECT f.name AS ForeignKey
FROM sys.foreign_keys AS f 
WHERE OBJECT_NAME(f.parent_object_id) = 'myTableName'
)
begin
    ALTER TABLE myTableName
    WITH CHECK 
    ADD CONSTRAINT [FK_myTableName_otherTable] 
    FOREIGN KEY([columnName]) 
    REFERENCES otherTable ([otherColumn])
end

if not exists (
    SELECT f.name AS ForeignKey
    FROM sys.foreign_keys AS f 
    WHERE OBJECT_NAME(f.parent_object_id) = 'myTableName') 
begin
    ALTER TABLE myTableName
    WITH CHECK 
    ADD CONSTRAINT [FK_myTableName_otherTable] 
    FOREIGN KEY([columnName]) 
    REFERENCES otherTable ([otherColumn])
end