我的表中有一个名为 MealType
( VARCHAR
) 的列,其中 CHECK
的 {"Veg", "NonVeg", "Vegan"}
约束
这将负责插入。
我想显示这些选项以供选择,但我无法找出 SQL 查询来找出表中特定列的约束。
乍一看 SQL Server 中的系统表,我似乎需要使用 SQL Server 的 API 来获取信息。我希望 SQL 查询本身能够得到它。
我的表中有一个名为 MealType
( VARCHAR
) 的列,其中 CHECK
的 {"Veg", "NonVeg", "Vegan"}
约束
这将负责插入。
我想显示这些选项以供选择,但我无法找出 SQL 查询来找出表中特定列的约束。
乍一看 SQL Server 中的系统表,我似乎需要使用 SQL Server 的 API 来获取信息。我希望 SQL 查询本身能够得到它。
此查询应向您显示表上的所有约束:
select chk.definition
from sys.check_constraints chk
inner join sys.columns col
on chk.parent_object_id = col.object_id
inner join sys.tables st
on chk.parent_object_id = st.object_id
where
st.name = 'Tablename'
and col.column_id = chk.parent_column_id
可以用这个替换select语句:
select substring(chk.Definition,2,3),substring(chk.Definition,9,6),substring(chk.Definition,20,5)
SELECT obj_table.NAME AS 'table',
columns.NAME AS 'column',
obj_Constraint.NAME AS 'constraint',
obj_Constraint.type AS 'type'
FROM sys.objects obj_table
JOIN sys.objects obj_Constraint
ON obj_table.object_id = obj_Constraint.parent_object_id
JOIN sys.sysconstraints constraints
ON constraints.constid = obj_Constraint.object_id
JOIN sys.columns columns
ON columns.object_id = obj_table.object_id
AND columns.column_id = constraints.colid
WHERE obj_table.NAME='table_name'
ORDER BY 'table'
感谢 orgtrigger 的例子!我对其进行了改进,以便能够删除不必要的约束(然后在需要时创建其修改版本)。也许此代码对任何人都有用。
-- removing old constraints
DECLARE @ConstraintNames TABLE (Name VARCHAR(MAX), RowNum INT)
DECLARE @TableName VARCHAR(100) = 'HubSpot'
INSERT @ConstraintNames
SELECT [constraint].name,
ROW_NUMBER() OVER (ORDER BY [constraint].[name]) AS RowNum
FROM sys.default_constraints [constraint]
INNER JOIN sys.columns col
ON [constraint].parent_object_id = col.object_id
INNER JOIN sys.tables st
ON [constraint].parent_object_id = st.object_id
WHERE
st.name = @TableName
AND col.name IN ('ForceUpdateOnImport', 'ForceUpdateOnExport')
AND col.column_id = [constraint].parent_column_id
SELECT * FROM @ConstraintNames
DECLARE @i INT = 1,
@count INT,
@constraintName VARCHAR(MAX),
@sql VARCHAR(MAX)
SELECT @count = COUNT(1) FROM @ConstraintNames
WHILE @i <= @count
BEGIN
SELECT @constraintName = cn.Name FROM @ConstraintNames cn WHERE cn.RowNum = @i
SET @sql = 'ALTER TABLE ' + @TableName + ' DROP CONSTRAINT ' + @constraintName
EXEC (@sql)
SET @i = @i + 1
END
下面有助于检查和默认约束。我将它用于隐式约束,以提供名称应该是什么的指导。如果您删除 where 子句之后的所有内容,它应该适用于任何检查/默认约束。
SELECT /* obj_table.NAME AS 'table',
columns.NAME AS 'column',
obj_Constraint.NAME AS 'constraint',
obj_Constraint.type AS 'type',
sss.name as 'schema',*/
'ALTER TABLE [' + ltrim(rtrim(sss.name))+'].['+ltrim(rtrim(obj_table.name)) + '] DROP CONSTRAINT [' + obj_Constraint.NAME + '];' As 'Wrong_Implicit_Constraint',
'ALTER TABLE [' + ltrim(rtrim(sss.name))+'].['+ltrim(rtrim(obj_table.name)) + '] ADD CONSTRAINT [' + CASE obj_Constraint.type
WHEN 'D' THEN 'DF' WHEN 'F' THEN 'FK'
WHEN 'U' THEN 'UX' WHEN 'PK' THEN 'PK' WHEN 'N' THEN 'NN' WHEN 'C' THEN 'CK'
END + '_' + ltrim(rtrim(obj_table.name)) + '_' + columns.NAME + ']' +
CASE obj_Constraint.type WHEN 'D' THEN ' DEFAULT (' + dc.definition +') FOR [' + columns.NAME + ']'
WHEN 'C' THEN ' CHECK (' + cc.definition +')'
ELSE '' END +
';' As 'Right_Explicit_Constraint'
FROM sys.objects obj_table
JOIN sys.objects obj_Constraint ON obj_table.object_id = obj_Constraint.parent_object_id
JOIN sys.sysconstraints constraints ON constraints.constid = obj_Constraint.object_id
JOIN sys.columns columns ON columns.object_id = obj_table.object_id
AND columns.column_id = constraints.colid
left join sys.schemas sss on obj_Constraint.schema_id=sss.schema_id
left join sys.default_constraints dc on dc.object_id = obj_Constraint.object_id
left join sys.check_constraints cc on cc.object_id = obj_Constraint.object_id
WHERE obj_Constraint.type_desc LIKE '%CONSTRAINT'
AND RIGHT(obj_Constraint.name,10) LIKE '[_][_]________' --match double underscore + 8 chars of anything
AND RIGHT(obj_Constraint.name,8) LIKE '%[A-Z]%' --Ensure alpha in last 8
AND RIGHT(obj_Constraint.name,8) LIKE '%[0-9]%' --Ensure numeric in last 8
AND RIGHT(obj_Constraint.name,8) not LIKE '%[^0-9A-Z]%' --Ensure no special chars
最简单快捷的方法是使用: